Vibration coming on at 65 mph with the drive shaft “OFF”.. When drive shaft is “ON”, vibrations is at 25-40 and 60-70 mph..

Issue occured after a lift with TG 5”. First install was done incorrectly and I busted the CV double cardan joint. I had a shop balance and install a new shaft and check the U-Joints.. After the new rebuilt shaft the vibration was reduce by 80%. I took off the rear drive shaft and put that in gear all the way to 65mph where I felt a slight vibe. There it was pretty consistent. I need to know what can cause that vibration??

86 T4R SAS / Duals

My current measurements:

39” long Driveline / dual cases

TC = 5*
Shaft = 18*
Pinion = 17*

 

First have all the tires re-balanced.

Then shake the shaft to see if its loose at the T-case or pumpkin.

Mine wound up being the tail shaft bearing in the T-case and pinion bearings in the pumpkin.

 

checked!! and checked!! vibrations seems to occur when i accelerate or steady on gas at that speed. Right with I let foot off gas. its smooth and quite.