Driveshaft install - won't slide forward!

Thanks for the suggestions guys. I ended up just calling it a night and I'll try again tomorrow evening, it's about 20 minutes away at my in-laws house.

Right now it's in the air front and rear on stands. I think my first matter of business tomorrow will be to let the front down on the ground and raise the rear as high as possible so I have a bit more room in the back. I'll pull the driveshaft out again, shine a light in the tail shaft just to make sure nothing is out of place, rub some more fluid on the driveshaft and give it a few whacks with the hammer if everything seems like it should work. It was still a good night though, after about 3 weeks, the car is back together and running with no leaks!