1991 vibration between 50-70mph

my 91 4x4 has a fresh rebuilt tranny, has vibration from 50-70 mph under acceleration, not u-joints or driveshaft, pulled d-shaft put in drive and pressed gas still vibrates???? any ideas???tranny shifts and drives perfect.:banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

Did this start after the trans was done?

Yes, it did start after the tranny was rebuilt, but drove to oklahoma twice no problems,wife drove it all day no problem, then i thaught it was a little low on fluid added some....overfilled it by 1 and a half courts,drove to work, didn't realize it was overfilled and started vibration couple of days later, drained fluid out and filled back up to normal level....vibration not as bad but still there. It also will vibrate in neautral or park at whichever rpm it is at when i push the gas down. Only vibrates at that one rpm when in park or neautral...any other rpm lower or higher does not vibrate at all????:screwy: :screwy:

Sounds like an out of balance or loose torque convertor or flywheel. Engine or trans mounts another possibility.

well i checked the flywheel and torque converter everything looks good from what i can see, i did unbolt torque converter and turn flywheel to line up on another holes and it seemed to help alot but is definatley still there as far as vibration...just not as bad.does that tell you anything???? Also i installed new detent cablt on tranny and got it adjusted to where it would shift good... but still sticks...is the tc valve sticking in tranny?? if so how do i fix that??????Please help!!:rofl: :rofl:

Sounds like the valve or linkage in the valve body is an issue. I would disconnect the convertor run it and see if the vibration goes away if so the convertor is bad, if not it gets tougher, harmonic balancer coming apart, cracked or bad flexplate/flywheel. Why is this your headache with a redone trans?