I have read some threads on this matter. My truck has been meticulously maintain as I bought new in 05. Redid all shocks, ball joints, tie rod ends. Had the drive shaft (and balanced) replaced with new u joints and yoke. Just had Michelin ltx 2 all replaced by Michelin bc of some bum tires, all road force balanced. Truck rides smooth as silk except for this vibration on highway around 75 mph. Tranny is fine, carrier is good, clutch pacs, couple shops just threw their hands in the air and said need to replace whole rear diff. bc its the last thing they came up with. Has anyone had any of these issues? have they found anything in particular in rear diff. that they fixed instead of a replacing whole unit? I have changed all my fluids way before required service just to be ahead of problems .. just stumped.

 

I'd still suspect tires at that speed just sayin

 

I wish it was.. Michelin put 4 brand new tires on it, my good road forced balanced them. The rear has a clunk sound when starting off. It has new shaft and u joints , out of options at this point.

 

One or 2 piece drive shafts in it?

 

The shaft that was replaced was a one piece, came with new ujoints and yoke, and has been balanced

 

I would find a shop that does dynamic tire balancing as opposed to static balancing.