i have a 99 ram 1500 5.9L automatic everything was great with the truck, then the trans went, i replaced the trans with a trans from a donor truck with 60,000. my truck has 156,000. before i took the trans out of the other truck i ran the truck and everything was PERFECT with that trans and ever since that day (a month ago) i have a nasty driveline shake. it starts around 25mph and goes on. it doesnt shake the truck at all, its def in the driveline somewhere, like the transfer case or rear shaft. at higher speeds my 4 wheel drive shifter goes nuts. it ONLY shakes when i am on the throttle. the second i get off the throttle at any speed......its smooth as can be again. and if i put it into neutral at any speed and rev it up....its smooth. its only when the driveshaft is under torque. the truck is an extended cab reg box. and it is lifted roughly 4 inches and on 35's. But this problem i doubt is lift related bc it was fine for months lifted. ??? U joint maybe ???

 

If it is a 2 pc. driveshaft, it's probably the mid shaft bearing.

 

one piece shaft with a slip yoke on transfer case side

 

u joints. grab the drive shaft at the pinion and give it a good shake/twist, then do the same at the slip yoke. i bet you'll see the u joints move, which is a bad thing.

 

After thinking,it has to be internal,since it started after the tranny change(torque converter,flex plate,output shaft,etc.)

 

i missed that part. did you put a new torque converter in there with the new transmission?

 

He didn't say it was new, just replaced

 

i used the torque converter from the new trans.....which has 60,000 on it

 

So it's not a "new trans" it's used,with 60k on it.If it has any kind of warranty, I would take it back where it came from.

 

i think ill start with some u joints first....i have one u joint with slight play in it....ill see if that makes a difference first. the trans came out of a truck that i know. which was my friends and it had low mileage but the body went to **** on it so he parted it out and i took the trans. i know the trans is good tho, i was in the truck on a daily basis...and there was never an issue