The block is slightly different. The differences have to do with having a differential in the oil pan. In the middle of the block there are several oil pan bolts than go in through the top b/c the diff. precludes being able to go in through the bottom. All of the major components, crank, rods, pistons, cylinder head, ect are the same. The block, oil pump, and of course the oil pan and it's associated hardware are the only engine parts I'm aware of that are different.