Originally Posted by toreador4x4
im still thinking that there was rust or soemthing between the two flanges (the one on the pinion and the one on the driveshaft) causing it not to run true. i will make certain that i clean them both thoroughly (sp?) before i assemble it. I still have to check the pinion flange for run out.
Definitely clean up the mating surfaces before reassembly.
Another thought: the factory matches the driveshaft yokes to the axle and t-case flanges and the parts should always be marked on disassembly so they go back together in the same orientation.
In your case, installing mismatched parts from 2 vehicles could cause a runout or imbalance stackup that would vibrate worse than on either of the original vehicles. You can try unbolting and rotating the driveshaft yoke 90, 180 and 270 degrees relative to the axle flange to test for the sweet spot. Same procedure at the transfer case flange.