67 C10 Driveshaft removal problem

[Phoax]

I'm trying to put in a different transmission and I can't get the driveshaft off. I fear I might have to either pull the engine+trans or disconnect the rear end and slide it back to get it off. I don't know what to do...

It's a 67' C10, one piece driveshaft.

This is the rear U joint. I can't get the U bolt out, it hit's the driveshaft.



Here is the front U joint.


I was thinking if I could raise the rear frame and sag the axle it might be enough. I'm working in my garage and don't have a good way to do that and I'm not sure it would even work.

Do you guys have any suggestions?