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Old 06-11-2018, 10:59 PM   #1
GMC85HighSierra
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Need help IDing 1/2 axles

Hi all, I was looking at some axles I have, and I was trying to ID the axle ratios for my front and rear axle. I took the diff covers off and found the numbers on the ring gears. Here's what I found:

Front axle: 2 GM 3984828 13 40 78

Rear axle: 3817779 14:43 GM 11762

I attached pics of each ring gear numbers; these were the best pics I got. I'm pretty sure I wrote all of the numbers down right. I determined that the front has a 3.08 ratio I think, and the rear has a 3.07 ratio. I just want to double check that I did this right, so I don't clean up a set of axles if they don't match. Not sure if it helps but the front is a 10 bolt and the rear is a 12 bolt. Thanks
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Old 06-12-2018, 01:29 AM   #2
Irish1941
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Re: Need help IDing 1/2 axles

Both are 3.07
40 divide by 13=3.07
43 divide by 14=3.07
Divide ring gear teeth by pinion teeth
However looking at those pictures they are both at end of their life.
Nothing you can use..
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Old 06-12-2018, 08:26 AM   #3
GMC85HighSierra
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Re: Need help IDing 1/2 axles

Ok; thanks. I thought that they were the same, but just wanted to double check. They're actually still useable, the pics make them look worse than they are. I will be going through and cleaning up the axles now that I know they match. Thanks
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