I guess I'm not quite sure what type of driveshaft you're dealing with. I just assumed it was a solid shaft. Didn't realize it was some sort of two piece splined shaft with a slip joint.
I didn't read all of the posts above very well. Probably not your original post that well either. Lol.
Just interjecting my opinion trying to give you some ideas.
No worries, just for clarity, here's the shaft in question: