I replaced my rear pinion seal in my '90 pickup, extended cab 4x4 22r-e.

Now I've got a pretty bad vibration coming from the rear of the vehicle at speeds above 40MPH. It seems to be worst when neither accelerating nor decelerating, going along on the flat with the throttle just feathered.

I tried flipping the shaft 180 on the rear diff slip yoke flange, in case I'd got it turned when doing the seal - but no difference. (it's a rectangular flange, so there's only 2 ways it could hook up.)

Side note: I also greased the double cardan joint while I was down there, don't know if that could have done it.

oh, and it's got 198,000 miles.

Ideas?

 

Not lifted, stock suspension.