Damn, replaced driveshaft support + bearing, now have minor vibration!
 

Drove about 3500 miles a month before, no problem, other than filter.

I replaced support + bearing - as I could feel a bad vibe when starting out.

I used a automatic center punch to mark - front ds to rear ds, front flange

to fr ds, rear ds to rr flange.

Flex discs no cracks, and bolt surfaces cleaned, did not line up marked ds

ends to flanges.

Lined up marks only on both ds's, had ds vibe about 50mph.

Maybe ds marks were off, moved one spline, as marks were close.

Vibe at 45mph.

Any ideas?

Most likely that's what happened.

I had a similar issue after I replaced a tranny plus the parts you are dealing with. This is what was recommended and it worked like a charm.

Get under the beast; loosen the big collar nut. Make sure the vehicle weight is fully down on the suspension. Ramps under the rear wheels work well enough for this and will still allow enough room to get under the car. Bounce the rear by pushing down on the rear bumper a few times to settle everything out. Tighten the collar nut.

This little dance to the driveline gods got rid of any trace of vibration for me. ymmv, but it looks like you have done most everything else. Might be worth the thirty minutes it takes to try it.

Sam

AD's trick for this
 

DO Not fully torque either the center support bolts or the BIG NUT,UNTIL
you've rolled the Chassis back and forth 5 or 6 times 15 to 20 feet.
This Pre-Sets the driveline length.

Thanks for the input!

Mine was the tranny mount. Didn't notice the vibe til I replaced what you did. I think the rest of the driveline was originally absorbing the vibration.

Dang it, this is exactly the situation I have right down to punch marking the ds halves. I have done both the bounce and lthe loosen and roll scenario to no avail.
I have not pulled the shaft out yet and likely will not till the car is parked for winter.
I will be interested in your progress

If all else fails to solve the vibration pull the drive shaft and check the u-joint. It should be smooth in both direction but rarely is. They usually "wear in" and get stuck or seized with some resistance to flexing in one or both directions and that is the cause of many vibrations. Some people have had luck re-aligning the driveshaft by shimming the center support with washers but that is hit and miss and only masks the problem. The only way to fix it is to have the driveshaft rebuilt and the bad u-joint replaced.