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3.94 & 3.55 differential differences

Wha's the reason for this?
The purpose of this write-up is to give you a clear difference when performing the 3.55 transmission mod on your 2gnt. You don't want the wrong differential gear in the wrong transmission or catastrophic damage will occur.

As you can notice in this picture, the differentials look the same. This writeup is going to tell you how to distinguish the two.

This first picture is the differentials side by side. Can you tell the difference by looking at them? (picture below)

The first way to tell them apart is to find one of your transmissions. Look at this picture. The output shaft splines. They sometimes have what's called hash ID markings. They're little grooves cut out on splines on different transmissions JUST for this purpose. This picture, the 3.94 trans, does NOT have the ID markings. (picture below)

The output shaft on that picture doesnt have any ID markings on it. So, that means the differential matches up with that transmission right? Here's a pic of the differential that doesnt have ID markings. (picture below)

Now, THIS is a picture of the 3.55 differential. See the ID markings in the center of the splines? (picture below)

The other transmission, the 3.55, does have these markings on its output shaft so there is your reference.

There is another way to tell. Measure the ring gear. The 3.94 is 1/8" of an inch larger than the 3.55. Here is a pic of the 3.55. (pic below)

Now, here's a pic of the 3.94 measurement. Very hard to tell, but you will notice a 1/8" of an inch difference if you measure yourself. (below)

I hope that this keeps people from blowing up some trannies :)

Document statistics: Last modified on 2009-07-11 01:03:26 by 420agreenvilleSC

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