I have what I believe to be a 3 series 8.2 differential in my garage sitting in a box. How do I make sure that is what I have before I go and start ordering parts for it??

For a 10 bolt 8.2" casting number on the carrier should be ED321182 for a 2.73:1 gear ratio and lower numbered gear.
The other possible 10 bolt 8.2" casting number should be EDB301163 for a 3.08:1 gear ratio and higher numbered gear (lower ratio).
For the 10 bolt 8.5" casting number on the carrier should be 410409N 2 for a 2.56:1 gear ratio and lower numbered gear.
10 bolt 8.5" casting number on the carrier should be 410408N 3 for a 2.73:1 & up.


Larger Dave

The only markings that I see on mine are GM72 and also 3878438, any ideas what in the world this is??

Do you have any pictures?

Here are the pics of the diff I have
http://i5.photobucket.com/albums/y178/l1tech/DSC01312.jpg
IMG]http://i5.photobucket.com/albums/y178/l1tech/DSC01311.jpg[/IMG]
http://i5.photobucket.com/albums/y178/l1tech/DSC01314.jpg
http://i5.photobucket.com/albums/y178/l1tech/DSC01313.jpg
http://i5.photobucket.com/albums/y178/l1tech/DSC01315.jpg
IMG]http://i5.photobucket.com/albums/y178/l1tech/DSC01316.jpg[/IMG]

and a few more
http://i5.photobucket.com/albums/y178/l1tech/DSC01311.jpg
http://i5.photobucket.com/albums/y178/l1tech/DSC01316.jpg

It looks like a 3 series. Set it on a flat surface on the bearing that is on the ring gear side. Measure from the flat surface to the mounting surface for the ring gear. This should be right at 2 inches for a 3 series. Also check the size of the bolt holes. A 8.2 should accept a 3/8 bolt, but not a 7/16 bolt. If the 7/16 bolt goes in the holes then it is probably a 8.5 differential.