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Old 02-08-2007, 05:13 PM   #1
TooT
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Rearend ID help?

We have a 6 lug posi but dont know what the gears are....here are some numbers we got off of it. 3817776H? and a A217. can anybody help? it came out of a 68 burban.
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Old 02-08-2007, 05:20 PM   #2
Longhorn Man
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Re: Rearend ID help?

why not pull the cover off and count the teeth? You divide the # of drive tteth by the number of driven teeth. Anything coulda happened in the last 39 years of that suburban's life, and the one thing that DIDN'T happen nearly enough, is diff oil being chainged. It's probably 20 years overdue for one, leaving the oil only working at 50% (worst case..assuming not contaminated)
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Old 02-08-2007, 05:31 PM   #3
GREASEMONKEY72
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Re: Rearend ID help?

just pull the cover and count them and clean as much of the old oil as you can out of there im sure its black and stinkier than normal and put some new stuff in there and make it easier on the gears with the nice new oil
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Old 02-08-2007, 06:01 PM   #4
tphsmith
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Re: Rearend ID help?

if you drain the oil and remove the back cover rotate the rear end with the cover off you would be able to see the stamed code on the gears and check the code out on a gear chart that is avaiable on the forum here, matter of fact Im pretty sure it wasif I recall Longhorn man helping me decode mine
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Old 02-08-2007, 06:08 PM   #5
1969k10stepside
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Re: Rearend ID help?

Check for the 2 sets of numbers and see what ratio they are that way.Here is a list.

Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9

Last edited by 1969k10stepside; 02-08-2007 at 06:08 PM.
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Old 02-08-2007, 06:22 PM   #6
GREASEMONKEY72
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Re: Rearend ID help?

mine is a 3.07 and a when you find the numbers you can look at the chart or divide them, drive divided by driven example 43 divided by 14 = 3.07
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