How To Air Seal Your Chimney Flue With A Chimney Balloon

How To Air Seal Your Chimney Flue With A Chimney Balloon

Chances are if you have a fireplace you’re losing heat through the chimney when you’re not burning the fire. Most chimneys don’t air seal well and are notoriously leaky. Or as I like to say, “Leakier than a porcupine’s water bed.”

Most fireplaces have a cast iron damper in the firebox. The dampers usually don’t seat well and allow a lot of air to get by anyways. The most effective way to seal a chimney is going to be to get up on your roof and seal the top of the chimney, this usually tends to be a little more permanent so it could be a good solution if you don’t plan on using your fireplace.

But if you plan to use the fireplace occasionally you may want a less permanent solution. An inflatable chimney balloon or bladder could be a good solution for you. They are relatively easy to install will only take you 5-10 minutes.

You can see the one I installed in my home and how I did it here:

Here’s an example of an inflatable balloon you use to temporarily seal your chimney:

How To Find Your Rear Differential Gear Ratio

How To Find Your Rear Differential Gear Ratio

Ever wonder how to find the gear ratio for your rear differential? This will help you find your gear ratio on a Ford or GMC/Chevrolet Truck.

First, you’re going to need to locate the manufacturer’s sticker on your truck with the code. Here is a video that will show you where to find that sticker:

Ford places their sticker on the driver’s side door at about thigh height. It’s visible when you open the door (usually on the door frame).

GM has a sticker placed in the glove box. If your GM vehicle doesn’t have this sticker (sometimes they don’t unfortunately) you may need to take your VIN to a dealer ask them to look it up for you.

Second, cross-check the code on your sticker with the ones listed below. This is usually a little easier on a Ford than GM. I’ve listed below all the axle codes that I am aware of for these manufacturers. Keep in mind if your rear differential has ever been modified or replaced with another, these codes may no longer represent your actual rear differential gears.

Ford Axel Codes and Their Corresponding Information

Axel Code (From Door Sticker)Axel TypeCapacity IbsRATIOYear
01 Ford 9″28002.75 
02Ford 9″28003.00 
04Ford 9″28003.25 
07Ford 9″28002.47 
13Ford 9″37502.751981-1983
13Ford 8.8 4.111985-1986
14Ford 9″37503.001981-1986
15Ford 9″37503.251981-1982
15Ford 3.31 
15Ford 9″37502.731983
16Ford 9″37503.50 
16Ford 3.73 
17Ford38003.311995 / 1999-2002 / Expedition
17Ford 3.551998
17Ford 3.731997
17Ford 9″37502.47 
18Ford 8.838003.081983-1986
19Ford 8.838003.551983-1986 / Expedition
23Dana 6053003.54 
24Dana 6053003.73Econoline
25Dana 6053003.33 
26  3.73F-250
27  3.31F-250
27Dana 7074004.10 
28Dana 7074004.56 
29Ford 10.25″53003.551991
31  3.73F-250 / Excursion
32Dana 6153003.00 
33Dana 6162503.54 
33Ford 4.30F-250
34  3.73Econoline
35  4.09Econoline
36Dana 7074003.731980
36  4.56F-250
37Dana 6053003.54 
38Dana 6053003.73 
39Ford 10.2562503.551991 Econoline
41  3.73F-350
43  4.30F-350
46  4.56F-350
49Ford 10.2574003.551991
51Dana 70 HD 74003.73 
52Dana 70 HD74004.10Econoline
53Dana 70 HD74004.561982
53Dana 70 HD74003.541983-1986
56  4.10Econoline
61  3.73F-350
63Dana 82003.54 
63  4.30F-350
66  4.56F-350
69Ford 10.2582503.25 
73  4.30F-450
75  5.38F-450
78  4.88F-450
81  3.73 
81  4.63Econoline
82  4.10F-350
83  4.30F-350
86  4.56F-350
88  4.88F-350
95  5.38F-550
98  4.88F-550
B5Dana 60 – Limited Slip53003.33 
B5Ford 10.25 – Limited Slip 4.10 
B6Ford – Limited Slip53003.55 
B6Ford – Limited Slip 3.73 
B7Ford – Limited Slip53003.73 
B9Ford 10.25 – Limited Slip 3.55 
C1Ford – Limited Slip 3.73F-250 / Excursion
C2Dana 61 – Limited Slip53003.00 
C2Dana 61 – Limited Slip53003.54 
C2Dana – Limited Slip62504.10F-250 / Excursion
C3Dana Limited Slip62503.54 
C3Ford – Limited Slip 4.30F-250 / Excursion
C5Ford 10.25 – Limited Slip 4.10 
C6Ford – Limited Slip 4.56F-250
C7Dana 60 – Limited Slip53003.54 
C9Ford 10.25 – Limited Slip 3.55 
D1Limited Slip 3.73F-350
D2Limited Slip74004.10 
D3Ford Limited Slip 3.54 
D3Dana – Limited Slip62504.10 
D3  4.30F-350
D5Ford 10.25 – Limited Slip74004.10 
D6Limited Slip 4.56F-350
D7Dana 70 – Limited Slip53004.10 
E1Ford – Limited Slip 3.73 
E2Dana 70 HD – Limited Slip74004.10 
E3Limited Slip 4.30F-350

2004 Ford Super Duty Axle Codes:

31 — 3.73 non-limited slip, F-250/Excursion
32 — 4.10 non-limited slip, F-250
41 — 3.73 non-limited slip, F-350
61 — 3.73 non-limited slip, F-350
73 — 4.30 non-limited slip, F-450
75 — 5.38 non-limited slip, F-450
78 — 4.88 non-limited slip, F-450
81 — 3.73 non-limited slip, F-350
88 — 4.88 non-limited slip, F-350
95 — 5.38 non-limited slip, F-550
98 — 4.88 non-limited slip, F-550
C1 — 3.73 limited slip, F-250/Excursion
C2 — 4.10 limited slip, F-250/Excursion
C3 — 4.30 limited slip, F-250/Excursion
D1 — 3.73 limited slip, F-350
D2 — 4.10 limited slip, F-350
D3 — 4.30 limited slip, F-350
E2 — 4.10 limited slip, F-350
E3 — 4.30 limited slip, F-350
EW — 4.10 limited slip, F-350 (ambulance package)
F1 — 3.73 limited slip, F-350
F2 — 4.10 limited slip, F-350
F6 — 4.56 limited slip, F-350
G3 — 4.30 limited slip, F-450
G5 — 5.38 limited slip, F-450
G8 — 4.88 limited slip, F-450
GW — 4.88 non-limited slip, F-450
K5 — 5.38 limited slip, F-550
K8 — 4.88 limited slip, F-550
KW — 4.10 non-limited slip, F-550

2007 Ford Super Duty Axle Codes:

37 — 3.73 non-limited slip
3L — 3.73 limited slip
41 — 4.10 non-limited slip
43 — 4.30 non-limited slip
48 — 4.88 non-limited slip
4L — 4.30 limited slip
4N — 4.10 limited slip
4W — 4.10 limited slip (ambulance package)
53 — 5.38 non-limited slip
5L — 5.38 limited slip
8L — 4.88 limited slip

2008 Ford Super Duty Axle Codes:

35 = 3.55 non-limited slip
3J = 3.55 limited slip
37 = 3.73 non-limited slip
3L = 3.73 limited slip
4L = 4.30 limited slip
4N = 4.10 limited slip

But wait…. there’s more. Here’s another chart. Brace yourself.

Axle CodePositractionRatio
005-JLimited Slip Differential 3.27
12Conventional non-Positraction Differential2.73
16Conventional non-Positraction Differential3.73
17Conventional non-Positraction Differential3.31
18Conventional non-Positraction Differential3.06
19Conventional non-Positraction Differential3.55
23Conventional non-Positraction Differential3.54
24Conventional non-Positraction Differential3.54
25Conventional non-Positraction Differential4.10
026-FConventional non-Positraction Differential 2.73
29Conventional non-Positraction Differential3.55
31Conventional non-Positraction Differential3.73
32Conventional non-Positraction Differential4.10
33 (1992-1998)Conventional non-Positraction Differential3.54
33 (1999-2002)Conventional non-Positraction Differential4.30
34Conventional non-Positraction Differential3.73
35Conventional non-Positraction Differential4.10
36Conventional non-Positraction Differential4.56
39Conventional non-Positraction Differential3.55
040-LConventional non-Positraction Differential 3.08
41Conventional non-Positraction Differential3.73
42Conventional non-Positraction Differential4.10
43Conventional non-Positraction Differential4.30
45Conventional non-Positraction Differential4.10
46Conventional non-Positraction Differential4.56
49Conventional non-Positraction Differential3.55
52Conventional non-Positraction Differential4.10
054-JConventional non-Positraction Differential 3.27
56Conventional non-Positraction Differential4.10
58Conventional non-Positraction Differential4.86
61Conventional non-Positraction Differential3.73
62Conventional non-Positraction Differential4.10
63Conventional non-Positraction Differential4.30
65Conventional non-Positraction Differential4.10
66Conventional non-Positraction Differential4.56
68Conventional non-Positraction Differential4.88
69Conventional non-Positraction Differential3.55
72Conventional non-Positraction Differential4.63
73 (1996-2000)Conventional non-Positraction Differential5.13
73 (2002)Conventional non-Positraction Differential4.30
75 (2002 Motor home – Dana 80)Conventional non-Positraction DifferentialSupply Bill of Material Number
75Conventional non-Positraction Differential5.38
78Conventional non-Positraction Differential4.88
81Conventional non-Positraction Differential3.73
82Conventional non-Positraction Differential4.10
83Conventional non-Positraction Differential4.30
86Conventional non-Positraction Differential4.56
88Conventional non-Positraction Differential4.88
95 (2002 Motor home – Dana 135)Conventional non-Positraction DifferentialSupply Bill of Material Number
95Conventional non-Positraction Differential5.38
98Conventional non-Positraction Differential4.88
102-AConventional non-Positraction Differential 3.31
113-ALimited Slip Differential 3.73
114-AConventional non-Positraction Differential 3.73
126-NConventional non-Positraction Differential 3.55
127-NLimited Slip Differential 3.55
130-NConventional non-Positraction Differential 4.10
131-NLimited Slip Differential 4.10
168-S Conventional non-Positraction Differential 4.10
169-SLimited Slip Differential 4.10
189-SConventional non-Positraction Differential 4.10
192-SLimited Slip Differential 4.10
199-RLimited Slip Differential 4.10
203-BLimited Slip Differential 2.73
209-ELimited Slip Differential 3.27
221-CLimited Slip Differential 2.73
223-CLimited Slip Differential 2.73
225-CLimited Slip Differential 3.08
227-CLimited Slip Differential 3.08
229-CLimited Slip Differential 3.27
231-CLimited Slip Differential 3.27
262-CConventional non-Positraction Differential 2.73
264-CConventional non-Positraction Differential 2.73
348FConventional non-Positraction Differential 3.27
350-FConventional non-Positraction Differential 3.08
352-FConventional non-Positraction Differential 3.08
354-FConventional non-Positraction Differential 3.73
355-FLimited Slip Differential 3.55
356-FConventional non-Positraction Differential 3.27
357-FLimited Slip Differential 3.55
359-FLimited Slip Differential 3.73
362-FConventional non-Positraction Differential 3.45
363-FLimited Slip Differential3.73
366-FConventional non-Positraction Differential3.45
367-FLimited Slip Differential3.73
368-FConventional non-Positraction Differential3.73
370-FConventional non-Positraction Differential 3.73
371-FLimited Slip Differential 4.10
372-FConventional non-Positraction Differential 4.10
374-FConventional non-Positraction Differential 4.10
430-FConventional non-Positraction Differential 3.07
434-FConventional non-Positraction Differential 3.27
501-FLimited Slip Differential 3.27
502-FConventional non-Positraction Differential 3.27
511-FLimited Slip Differential  3.27
515-FConventional non-Positraction Differential  3.27
610-BConventional non-Positraction Differential 3.27
612-BConventional non-Positraction Differential 3.55
613-BLimited Slip Differential 3.73
614-BConventional non-Positraction Differential 3.73
615-CLimited Slip Differential 4.10
616-BConventional non-Positraction Differential 4.10
619-ALimited Slip Differential 3.37
621-ALimited Slip Differential 3.73
625-ALimited Slip Differential 3.27
668-HConventional non-Positraction Differential 4.10
674-FConventional non-Positraction Differential 3.55
675-FLimited Slip Differential 3.55
696-HConventional non-Positraction Differential 3.73
697-HLimited Slip Differential 3.73
699-HLimited Slip Differential 4.10
710-AConventional non-Positraction Differential 3.55
711-ALimited Slip Differential 3.55
740-PConventional non-Positraction Differential 3.31
746-AConventional non-Positraction Differential 3.55
747-ALimited Slip Differential 3.55
802-CConventional non-Positraction Differential 3.31
820-CConventional non-Positraction Differential 3.55
821-CLimited Slip Differential 3.31
825-CLimited Slip Differential 3.55
832-JConventional non-Positraction Differential 3.31
833-JLimited Slip Differential 3.31
835-JLimited Slip Differential 3.08
845-MLimited Slip Differential 4.10
852-AConventional non-Positraction Differential 3.08
862-BConventional non-Positraction Differential 3.55
869BLimited Slip Differential 3.55
900-AConventional non-Positraction Differential 3.08
908-AConventional non-Positraction Differential 3.55
909-ALimited Slip Differential 3.55
930-AConventional non-Positraction Differential 3.31
935-CLimited Slip Differential 3.73
947FConventional non-Positraction Differential 4.63
948FConventional non-Positraction Differential 5.13
950-AConventional non-Positraction Differential 3.08
954-AConventional non-Positraction Differential 3.31
956-AConventional non-Positraction Differential 3.55
958-AConventional non-Positraction Differential 3.73
B4Limited Slip Differential3.73
B5Limited Slip Differential4.10
B9Limited Slip Differential3.55
C1Limited Slip Differential3.73
C2Limited Slip Differential4.10
C3 (1992-1998)Limited Slip Differential3.54
C3 (1999-2002)Limited Slip Differential4.30
C4Limited Slip Differential3.73
C5Limited Slip Differential4.10
C6Limited Slip Differential4.56
C9Limited Slip Differential3.55
D1Limited Slip Differential3.73
D2Limited Slip Differential4.10
D3Limited Slip Differential4.30
D5Limited Slip Differential4.10
D6Limited Slip Differential4.56
D403AConventional non-Positraction Differential 3.54
D404AConventional non-Positraction Differential 3.73
D454ALimited Slip Differential 3.73
D607AConventional non-Positraction Differential 4.10
D615JConventional non-Positraction Differential 4.09
D630JConventional non-Positraction Differential 3.54
D631AConventional non-Positraction Differential 4.10
D632AConventional non-Positraction Differential 3.73
D654ALimited Slip Differential 3.54
D808ALimited Slip Differential 4.10
E1Limited Slip Differential3.73
E2Limited Slip Differential4.10
E3Limited Slip Differential4.30
E6 (1992-1998)Limited Slip Differential4.10
E6 (1999-2002)Limited Slip Differential4.56
EW (1992-1999)Limited Slip Differential4.10
EW (2000-2002)Limited Slip Differential4.88
F1Limited Slip Differential3.73
F2Limited Slip Differential4.10
F3Limited Slip Differential4.30
F5Limited Slip Differential4.10
F6Limited Slip Differential4.56
F8Limited Slip Differential4.88
G3Limited Slip Differential4.30
G5Limited Slip Differential5.38
G8Limited Slip Differential4.88
GWLimited Slip Differential4.10
H5Limited Slip Differential4.10
H7Limited Slip Differential3.31
H8Limited Slip Differential3.08
H9Limited Slip Differential3.55
K5Limited Slip Differential5.38
K8Limited Slip Differential4.88
KWLimited Slip Differential4.10
W5Limited Slip Differential4.00

Thanks Ford. For all that code.

GMC / Chevrolet Axel Codes

RPO is the acronym for “Regular Production Option.” I’ve included some GM codes for front axels too, just in case you need it.

RPO CodeTypeRatio
F16Transaxle Final Drive2.53
F17Transaxle Final Drive2.84
F18Transaxle Final Drive2.65
F25Transaxle Final Drive3.32
F29Transaxle Final Drive2.82
F36Axle Front2.19
F45Axle Front2.93
F47Axle Front2.73
F57Axle Front3.15
F62Transaxle Final Drive2.39
F67Transaxle Final Drive3.19
F68Transaxle Final Drive3.45
F75Transaxle Final Drive3.18
F77Transaxle Final Drive3.73
F79Transaxle Final Drive2.97
F82Transaxle Final Drive3.23
F83Transaxle Final Drive3.05
F90Axle Front2.73
FA1Rear 2 Speed4.88/6.94
FA2Rear 2 Speed4.88/6.94
FH5Transaxle Final Drive2.81
FH6Axle Front3.64
FH7Transaxle Final Drive4.12
FH8Axle Front2.40
FH9Transaxle Final Drive2.60
FJ1Axle Front4.18
FJ2Axle Front3.74
FJ3Transaxle Final Drive3.35
FJ4Axle Front4.53
FJ5Axle Front4.19
FJ7Axle Front4.56
FP0Transaxle Final Drive2.55
FP1Transaxle Final Drive2.72
FP2Transaxle Final Drive3.58
FP3Transaxle Final Drive2.73
FP4Transaxle Final Drive2.69
FP5Transaxle Final Drive2.95
FP6Transaxle Final Drive3.54
FP7Transaxle Final Drive3.73
FP8Transaxle Final Drive3.54
FP9Transaxle Final Drive3.54
FQ2Transaxle Final Drive3.48
FQ3Transaxle Final Drive2.86
FQ4Transaxle Final Drive3.57
FQ6Transaxle Final Drive4.12
FQ8Transaxle Final Drive2.96
FQ9Transaxle Final Drive3.21
FR2Transaxle Final Drive2.93
FR3Transaxle Final Drive3.69
FR6Transaxle Final Drive3.84
FR7Transaxle Final Drive3.95
FR8Axle Front4.17
FR9Transaxle Final Drive3.29
FV0Transaxle Final Drive3.67
FV1Transaxle Final Drive3.72
FV2Transaxle Final Drive4.18
FV3Transaxle Final Drive3.11
FV4Transaxle Final Drive3.71
FV5Transaxle Final Drive4.19
FV6Transaxle Final Drive4.24
FV7Transaxle Final Drive4.29
FV8Transaxle Final Drive4.31
FV9Transaxle Final Drive4.53
FVOTransaxle Final Drive3.67
FW2Transaxle Final Drive3.06
FW3Transaxle Final Drive4.02
FW4Transaxle Final Drive3.89
FW5Transaxle Final Drive4.10
FW6Transaxle Final Drive3.42
FW7Transaxle Final Drive3.83
FW8Transaxle Final Drive4.28
FW9Transaxle Final Drive3.43
FWSTransaxle Final Drive4.10
FX1Transaxle Final Drive3.94
FX2Transaxle Final Drive2.66
FX4Transaxle Final Drive3.35
FX8Transaxle Final Drive3.61
FY1Transaxle Final Drive2.36
FY3Transaxle Final Drive3.79
FY5Transaxle Final Drive3.52
G11Transaxle Final Drive2.56
G44Axle Rear3.07
G72Axle Rear2.14
G75Axle Rear3.62
G76Positraction Rear 
G80Axle Positraction, Limited Slip
G81Positraction Rear Axle 
G82Axle Rear4.56
G84Axle Rear4.10
G86Axle Rear, Limited Slip
G87Ring Gear, 8.5″ 
G89Ring Gear, 7.5″
G91Special Highway Rear Axle3.08
G94Axle Rear3.31
G96Axle Rear3.55
G97Axle Rear2.73
GH0Axle Rear3.54
GH2Axle Rear2.29
GH3Axle Rear2.77
GH4Axle Rear2.92
GH7Axle Rear2.73
GJ1Axle Rear5.38
GJ2Axle Rear5.13
GK7Axle Rear4.78
GK8Axle Rear4.33
GK9Axle Rear4.63
GL0Axle Rear5.13
GL3Axle Rear6.17
GM1Axle Rear2.59
GM2Axle Rear3.44
GM3Axle Rear3.45
GM4Axle Rear3.67
GM5Axle Rear3.89
GM6Axle Rear4.22
GM7Axle Rear3.68
GM8Axle Rear2.56
GN9Axle Rear4.11
GS1Axle Rear2.73
GS3Axle Rear3.73
GS4Axle Rear3.70
GS5Axle Rear4.11
GS6Axle Rear4.56
GS8Axle Rear3.94
GT1Axle Rear2.56
GT2Axle Rear2.29
GT4Axle Rear (Dup of 5X1)3.73
GT5Axle Rear (Dup of GT8)4.10
GT7Axle Rear3.33
GT8Axle Rear (Dup of GT5)4.10
GU1Axle Rear2.41
GU2Axle Rear2.73
GU3Axle Rear2.93
GU4Axle Rear3.08
GU5Axle Rear3.23
GU6Axle Rear3.42
GU7Axle Rear2.77
GU8Axle Rear3.90
GU9Axle Rear3.91
GV0Axle Rear3.55
GV1Axle Rear2.73
GV2Axle Rear5.83
GV3Axle Rear3.08
GV4Axle Rear3.36
GV5Axle Rear3.55
GV7Axle Rear4.11
GV8Axle Rear2.72
GV9Axle Rear4.25
GW2Axle Rear2.56
GW3Axle Rear2.56
GW4Axle Rear3.31
GW5Axle Rear2.73
GW6Axle Rear3.27
GW8Axle Rear4.10
GW9Axle Rear (Dup of GU3)2.93
GX1Axle Rear3.70
GX2Axle Rear3.07
GX3Transaxle Final Drive3.33
GX4Axle Rear3.75
GX5Axle Rear4.09
GX6Axle Rear3.53
GX8Transaxle Final Drive3.74
GY2Axle Rear3.31
GY3Transaxle Final Drive4.29
GY4Axle Rear4.53
GY5Axle Front3.65
GY7Transaxle Final Drive4.18
GY9Axle Rear4.31
GYSTransaxle Final Drive3.65
H01Axle Rear3.07
H04Axle Rear, Single Speed4.11
H05Axle Rear3.73
H12Axle Rear, 21000 Lbs, Eaton 21065S, Single Speed
H42Axle Rear6.17
H43Axle Rear5.43
HA3Axle Rear, Single Speed5.29
HC4Axle Rear4.56
HC7Axle Rear, 7500 Lbs, Single Speed2.38
HC8Axle Rear, Single Speed, Truck3.21
HC9Axle Rear5.13
HE3Axle Rear, 3500 Lbs, Single Speed3.07
HE4Axle Rear3.40
HF7Axle Rear, 10000 Lbs, Dana 70, Single4.56
HF8Axle Rear4.88
HJ1Axle Rear4.55
HJ2Axle Rear5.86
HJ3Axle Rear4.75
HJ4Axle Rear6.50
HJ5Axle Rear5.57
HJ6Axle Rear4.78
HJ7Axle Rear4.88
HK1Axle Rear2.87
HK3Axle Rear6.14
HK9Axle Rear 10000 Lbs, Single Spd5.86
HO4Axle Rear4.11
HO6Axle Rear4.63

There you have a lot of rear differential axle codes. Hopefully the code you’re looking for it listed above… or it might really grind your gears. Pun intended.

Dodge or Chrysler… sorry, I got nothing for you.



In physics, Diffusion is the net movement of molecules or atoms from an area of higher concentration to an area of lower concentration.

In the building industry and building sciences, we most often use the concept of Diffusion to understand and/or anticipate how water will move through a material or an assembly of materials. Water, often in the physical form of water vapor.