Excelleration Vibration

between 2 and 4k RPM's I get a terrible vibration. it goes away when you coast either in or out of gear. if you are out of gear and rev the engine seems fine. only when in gear and accellerating does the vibration occur. some say U Joints, I had a 300lb load in and de-accellerated in gear which I think caused the vibration. any help would be greatful.

Typically a bad u-joint produces a momentary clunk when you accel/decel, not a continuous vibe. A bent/dented/out-of-balance drv shft can do that though, or a tranny problem, out-of-bal tire, lots of things.

well the tire issue is no good because I can coast at high speeds and get no vibration. I figure it has something to do with powering the wheels because that is when it happens. can you break the inner part of a drive shaft? it all happened because I was carrying a 300 lb load and accelerated and didnt pull it out of gear or shift higher. the truck wanted to role faster but being in the lower gear at higher speeds it tourqued somewhere.

Is the truck 4WD? If so, remove the rear DS and drive in 4 high and see if the problem goes away. If it does it could be the rear DS or the rear diff.

pulled the drive shaft, took it to my mechanic and he said my rear U joint was bad. he sent me to a specialist who charged me $25 to instal one. by the way I bought one from a store for $14, which I returned. I took me 2hrs to pull, learning curve and so on. it took me 1hr to put back. works great thanks for all the help.