I recently encountered the same problem. The internal splines on the yoke had twisted slightly (due to torque I guess)and wouldn't allow the yoke to slide back on the driveshaft. I removed the bolts from the 2 front rear spring shackles
AFTER I made sure everything was safely supported w/jackstands. That allowed the rear axle to move backwards enough on the rear shackles to drop the torque tube and remove the yoke. Most likely you'll need another yoke. This process with take time and can be dangerous so proceed carefully and a 2nd set of eyes won't hurt either. You could also try raising the rear and supporting the frame allowing the rear axle to sag down. This may give you the little bit of room needed to pry the joint apart at the universal. Something I didn't consider at the time but it may work. Good luck.

Ed