vibration trouble

Need some help sorting out a vibration on the 89 RRC under load at between 20 and 40 mph. We did a 2 inch lift (RN procomp kit) and the vibration appeared. We have ruled out the front propshaft, tightened everything up front, checked the transmission and motor mounts, and checked the rear propshaft. Not sure what else to look at - there is no more than normal play in the drivetrain and no abnormal sounds.

Moose suggested it could be carrier bearings...other ideas? I'm looking to check the obvious before digging deeper. And it seems it should be obvious since it appeared with the lift.

Any ideas would be appreciated.

RC

It's quite common to experience drive line vibrations after a lift, even if just a couple inches. Each truck seems to respond a little differently, some do it with 2" some with 3". It's most likely a driveshaft angle/alignment issue. Could just be the suspension bushings too. Could need driveshaft work even though they appear to be fine. There are many ways to correct them, search on sites like discoweb or D-90, lots of info on this problem at those sites.