1990 4.3 blazer 4x4

ya my problem is extrrrremly loud clunking and vioelnt vibrations from the passenger side under acceleration but i tried takeing all 4 wheels off the ground and reved it up in 4 wheel drive and no vibrations or clunks at all i have replaced cv axle, hub, ball joints, all ujoints and nothing helped the problem all of these things were bad though but just wernt the cause of the main problem really getting frestrated on this one....ill check the mount tomorow moring and see if that is it thanks guys.

oh ya and around 70 km before it switchs greas i can here and clicking and almost like a grinding from up front like something is trying to engage....

 

sounds like a trasfer case problem. Chain could be gettin ready to go or planetary is going out. It will only make noise under a load. so when you take all the wheels off the ground there really insnt any resistance to the drivetrain so you cant find it that way. Also check Transfer case crossmember mounts and your motor mounts. One could be out or have play in it and causing drivetrain to tweak under a load and be out of allignment causing all the noise and such.
simple to and I am sure you did, but are all your fluids up to level on your front and rear end. tranny and transfer case?