Driveshaft won't fit

I had my 727 out for the winter to do a quick inspection, and install a manual valvebody. Everything went back together as it came apart. I have also installed a 9.5" aftermarket converter. Converter was installed, fully seated, before mating transmission back to the engine and reinstalling in the car.

I don't recall the driveshaft being tight to come out, but upon trying to reinstall it today, with the yoke bottomed out in the trans, I can not get the u joint into the diff. The front of the car is jacked up, and the rear wheels on the ground. Something is off, and im not sure what. Should I try installing with the rear wheels off the ground as well? Seems to me that would make it even more difficult/shorten the distance. Maybe rotate the yoke on the diff and try reinstalling that way? Im stumped and annoyed, as Im really hoping this doesnt mean I need to pull the trans...