I am going to pick it up. He can not get it to replicate the shaking I am experiencing. I think I will just take your advice and check things out myself or just say screw it and live with it till I can trade this truck in.

 

I had a 94 1500 that would buck and shake at a certain speed and throttle position. Had it checked out numerous times by dealers, and none could get it to exhibit the symptoms I described to them. The truck was only a year old, and under warranty. I finally asked the service manager if I could take a mechanic out for a ride. Went to a country road that was flat and got the truck to show it's demon. Mechanic said, OOHH, yes, I can feel that. Turns out it was a cracked distributor cap. Point being, if no one can duplicate your trucks behavior but you, by all means take the mechanic for a ride. I don't know why you didn't do that in the first place. Might have saved said mechanic a lot of time examining your truck with no idea of the issue other than what you describe. Take him for a ride already!!!!

 

Well there is the problem. I have taken him for a ride in it and when I had it in a dodge I took their tech for a ride. Never shook. I swear my truck knows when a mechanic is in it. Haha.

 

That is extremely odd... I mean I know on older vehicles there was a harmonic balancer that could cause major shaking at certain speeds.... but I'm not sure our trucks have that.

Which leads me to one last item to check... Motor and Trans Mounts... If it only happens under load then it might be the motor and transmission mounts....

How many miles are on the truck? If it's over 100k then I'd definitely think that was a possibility. Have them check the motor mounts, or just replace them, because if it is a transmission or engine problem that is causing the vibration new motor mounts will stiffen it up and make it more apparent and thus narrowing your search down.

 

I checked motor mounts and trans mounts and so did the mechanic and all was good. He could not find one bad thing on this truck. The thing looks like it is brand new off the showroom floor. Only problem is the shaking that no mechanic nor myself can figure out. where was the harmonic balancer located at on the older trucks and what did it look like? Hopefully in a few weeks I am going to drop the driveshaft and get the balance checked and check my U joints. I am moving this weekend so I have to wait now. haha