CAN THE PINION ANGLE CHANGE ?

I asked about drive shaft length because, if you pull the shaft too far out of the back bushing, then the yoke sometimes starts whipping around not on the trans centerline.If this is allowed to continue, it wears the bushing tapered.
But before you drive yourself crazy, be sure you have isolated the vibration to not being in the wheels or tires,etc. I know you said it was fine until the swap,..............but

You didn't by any chance swap pinion yokes?