Absolutely. The yokes on each rotating section must be aligned.
So when you stab the slip joint, the yoke welded to the front tube
needs to be aligned with the yoke on the spline. Normally, being
one spline off is easy enough to see. This affects the rotational
velocity through the shaft, and will give vibration if not correctly
aligned. I usually put mine in gear with the front yoke horizontal
and stab the spline with the rear yoke also horizontal, but anything
to get them together is fine. After stabbing, take it out of gear
so you can turn the shaft to bolt up the differential.

Other problems could be a bad center bearing or a bent driveshaft,
maybe even a bad universal joint. Should be free, neither stiff nor
loose. (Same applies to the center bearing.)
--
George Downs Bartlesville, Oklahoma