help.... vibration

[usmp89]

i just converted my driveshaft from 2 piece to one piecei still have vibration from 45 mph and up. im going to rotate the shaft 180 degrees and see what that does, and im going to see if walmart will balance the tires again for free ( under warranty). it dissipated a little bit between the shop and my apartment(approx 60 miles). I set my cruise at 65 and the vibration dampened, as soon as i slowed down tho the vibration picked up again.it sounds like a dull rumble in the cab. i also put it in neutral and reved it up but it didnt seem to be coming from the engine. I reved it up in the shop ( i was standing in front and reving it up from the throttle body) and at about 3000 rpm there was a similar vibration.The truck drives a straight as it did before. the vibration feels like its coming from under my seat and thats about where the trans mount is. im thinking if rotating the shaft and tire balancing doesnt work im thinking its either the mount, flywheel, torque converter( the bearing)

anyone have a suggestion

 

[Ryannn]

Did you have the new shaft balanced?

 

[doorgunner]

Did you have the new shaft balanced?

+1

if it was custom made-are the NEW u-joints synchronized?

Did you put grease on the splined shaft?

Did you reset the pinion angle on the rear end?

 

[zacharry]

check to make sure that all the bolts are tight on the drive line, they have that four bolt pattern and some times they come loose, put some lock tight on them if you havent already and if that doesent work and it started happening right after you had the drivline put in or made, i would bring it back to the shop and have them rebalance it.