Originally Posted by lincpimp

Looks like you have the small plastic collar that goes around the "nose" of the diff case on backwards... You need to turn it around, as the V shaped slot that is in the collar mates with the chassis plate.

You 2nd pic shows the collar on backwards, and the 1st pic shows you need the diff to go in about 1/4" or more.

If this is not clear let me know and I can take a pic of a properly assembled bulkhead/diff assy.