So I checked for play... and there was PLENTY! Not the U-joints, but in the pinion. Thing was LOOSE, a good 1/8' of movement in all directions.
So I dropped the driveshaft and sure enough the pinion nut was loose as could be. I was able turn it by hand no problem.
I did a little research on torque specs for the pinion nut, looks like its a bit more complicated than that. I'm going to snug it up and hope it gets me home.
I'm going to bring it by my local rear end shop and see what they say, might be in the market for something a little more stout, and with POSI