drive shaft woes

[alderan33]

I need help with this one guys. It's a strange one. So I am restoring my 72 C10 and I have the bed off and have been working on the frame, front end, etc.. I have the motor out and decided to replace the u joints. No problems with them. I began reinstalling the rear section of the drive shaft (2 piece) and after securing the u joint to the rear end I attempted to bolt up the carrier bearing. And it is 1 1/2" too short to line up with the mount on the truck. I did nothing with the carrier bearing. I am stumped at why and how this could happen. The truck is a long bed. The only thing I can think of is the absence of all the extra weight from the bed makes it sit differently? I could really use some advice and I would be most appreciative of any help. Thanks!