Finally drove truck on maiden voyage. Though transmission was junk.

[old Chevy guy]

Took my newly rebuilt 71 c 20 for a ride after a year apart while doing a cab swap. Started out great then the farther I went the noisier it got. Thought somehow the 4 speed got junked while the truck was parked for almost 2 years before the swap and a year during. The truck picked up a wicked vibration and a howl the further I drove it Sunday. It was the maiden voyage, first drive further than just outside the garage after a long restore. At first I thought the transmission had a bad bearing then thought maybe rear end or carrier bearing on the driveshaft. Turned out to be the slip joint on the driveshaft was seized putting A ton of presume on the rear transmission bearings and the pinion. Someone at the local garage had suggested checking the carrier and when I looked at it with the wheels up on a jack while running in gear I thought it was the pinion. Upon trying to take the driveshaft out I discovered an unbelievable amount of pressure on the drive shaft in both directions,front and back. It was a struggle to get it out at all. When I unbolted the carrier it shot up to the top if the hole it goes through in the frame. Luckily my fingers weren't in the way. A lot of penatrating oil ,heating and beating later I got it apart cleaned it up and greased it, putting it back in and it seems so far to be all better. We will see. Must have gotten longer over some bumps and couldn't go back shorter due to rust. Has anybody else had that happen?