exhaust vs. driveshaft

My exhaust downpipe and my front driveshaft are currently trying to prove the laws of physics wrong. i had my trans out (5 speed on an 89 2 door) and upon putting everything back together, i've got a wicked bad racket going into 4wd. turns out the drive shaft is up against the exhaust.
any idea what i did wrong? i don't think the front shaft universal joint is gonna like life much with that much interaction.
thanks fellas and ladies,
Sam,

I just put my auto trans back in and had the same problem. I just loosened the bolts and rotated the pipe for more clearance then tightened them back up. Don't know if the pipe was bent or if your supposed to put it on cockeyed.

torn/displaced engine mount?

I recently replaced the driver's side motor mount with an OEM unit and the pass side looked fine. I don't know if it had something to do with the OEM part superceding to a new part. But it was never a problem until I did an R&R on my downpipe.