That last one is always a pain, its most likely because of the poly bushings, they don't allow nearly as much flex. It took me and a friend 2 days to get my last bolt in, actually, I could get it started, but it was always off a 1/2 or so. After 3 hours of wiggling and fucking with it we gave up. The next day we got it in under 10 minutes...go figure, lol.
just try raising/lowering/tilting/twisting the rearend, definitely need a friend, but it'll go.