Does the drive shaft need to be in time? on 1995 Chevrolet S10

I replaced tran and diff seals, there was no vibration before the seal replacement. now a noticeable vibration. checked rear u-joint saddle for miss alinement, but is in correct position.
Vibration subsides some after 65mph.

Asked by for the 1995 Chevrolet S10
2 answers 6 comments
If you replaced the pinion seal, did you torque the 'yoke' retainer nut correctly?
I torqued it at 140 '#
if its one piece drive shaft no it doesn't,double ck you work b4 you damage the diff gears
It's not a 1 piece shaft...has a slip joint and mount mid way back from trans
Long bed pick up would have been useful info! Bunch of S-10's!!! All u-joints have got to be in line with each other! Did you separate the shafts?
it's not a long bed, but is extended cab and all joints are in line
Same difference!! No other way to "time" a u-joint.
I called a Chev dealership and there service dept said it needs timed...remove rear joint from saddle and turn diff yoke 180 deg