I'm in the middle of a diff swap and I noticed the following difference (see pictures at bottom)
It is the small structure that is sandwiched between the bottom of the diff and the PPF with the 2 long bolts running through it. What I"m swapping out (3.9) has this piece bolted to the housing with 2 bolts. The diff I'm swapping in (4.3) has only 1 bolt. I'm assuming it's not a problem, but can anyone confirm?
http://imgur.com/8iItocU (side by side showing difference vs old diff being swapped out)
http://imgur.com/BZzcL9E (on the new diff ready to be sandwiched with the PPF)
http://imgur.com/ODTSANz (another comparison showing a missing bolt location)