You say it is there in neutral. Is it there if you shut off the engine at speed? If it is it can't be the torque converter or flex plate. If you decide to test this, be sure not to lock up the steering and remember you will loose power steering. The safest way to test this is not to use the ignition switch but to have a toggle switch in the cab with wires that go in to the coil + lead so you can make or brake that connection briefly while driving. Slip the truck into neutral and flip the switch. Notice if the shake goes away or not then flip the switch back on, restart the engine, and go back into drive. This is much cheaper than replacing the torque converter, not to mention the work.

 

seal,that is a good idea. i never thought of doing that but it makes good sence to try that.
i dropped the trans pan today,fluid was still good only had 5,000 mi on it,nothing in pan all was good. i adjusted the bands,drained as much fluid as i could from lines and cooler and all. i refilled it plus i added a bottle of LUCAS trans fix,figured it may help if it is the torque converter.
i also put in a new tps,it plays a part in locking up the torque converter.
just did this for some piece of mind. i will play with it some more tomarrow. thank you

 

ok took it out on INTERSTATE 10,took it up to 80mph,shut it down in neutral,i beleive the shake is still there. i may have to try it again to be positive. so that would suggest its not torque converter wright??
its 110 degrees here so its to hot to do anything else today. maybe next weekend it will be cooler like 99. ha-ha thank you

 

If the problem is still there when you shut off the engine at speed and go to neutral it can't be the torque converter or flex plate because they are not moving at that point.

 

thanks seal,
i will check it again during the week,but i believe the shake was still there with the truck off,just need to find smoother road.
i really wish i could just take it somewhere for them to find out this problem, no one is reliable,not even the DODGE dealers. should ride like a cadillac for how much is new,and the money i put in this.
i owned at one time or another 6 older mopar cars and trucks,never seen anything like this before. i am just puzzled!!! thank you

 

Not to diminish your problem but my truck, right off the showroom floor, never road like a cadillac. Never lose sight of the fact that it is an old truck with its older technology. It will never ride like a modern day vehicle.

 

seal, i had a few other dodges 78 d150,87 d150,92 ramcharger, they always had a good smooth ride to them,not to mention how reliable they all were. had a 04 hemi 4x4 also,it rode nice just ate lots of gas,just sold my 06 dakota in may,it also rode good,just not enough power.
i just never had one or any vehicle that once all this work was done to it that rode with a shake/shimmy,and no shops can figure it out??
thank you

 

well i come to this,it seems to be the rear springs. when i bought it in sep.09 the truck set level and a little low,so i put on rancho add-a-leafs,and gabrial vst shocks. the spring must have been bad then. now i believe they are worse,and the only thing holding up the back is the add-a-leafs and the new monroe sensatrac loadlevelers i just put on it.
if i push down on the rear bumper pass side,just giving it a quick bump down and let go,it shakes through the entire bed,looks like the shake i feel on the road,the driver side also does this but not as bad.
its now constantly there even when picking up speed,just not as bad as highway speed. its even there when i hit the brakes,it bounces.
this has got to be the problem,nothing else under truck is original except the rear springs???? thank you

 

well just got done putting on the new rear leaf springs.
took for a short ride, it takes bumps and bounces better. i'll be able to tell better during this coming week. it seems that the shake/vibration is a little less. it just feels like the rear end of this truck is to light and just bouncing around???? it still has a bounce when braking but from 20mph down. its not at highway speed if you hit the brakes. there now is nothing else underneath that i can change all is new,unless some new part is faulty, but what?? thank you

 

well drove to work,all highway @ 65-70 and its a hell of alot better. it takes road bumps better. the shake/vibration is still there slightly.
the only thing that concerns me is the possibility of something with the rear brakes. i have a shake/bunny hop useing the brakes, comes on from 35 mph down while braking. it seems like the rear brakes. could it have something to do with the ABS?? i have no ABS light on saying there is a fault?? every thing back there is all new. what could this be??? thank you