5000 drive shaft questions

[Paul Hill]

I have a 1986 5000 CSTQ with 334,000 miles on it. I had a mechanic drop the
center drive shaft and do a visual check of the center bearing and
universal joint, which he said looked fine. He greased the CV joints and
put the whole thing back. Now it vibrates slightly in the 50 to 60 mph range.

I just found an identical car to mine in the local scrap yard (actually
it's an '87 and mine is a late '86) which has only 110K miles on it (don't
ask me why it was scrapped, it's in better shape than mine and the owner
drove it to the scrap yard!! criminal!!). I snagged the drive shaft. So the
question is, how difficult is it to put a used shaft in and get it lined
up? Also, how much movement should there be in the rubber around the center
bearing? If you grab the shaft near the bearing and push it up and down and
side to side, should you be able to see movement and if so how much?

Paul