I have a 06 that shakes at about 1500 rpm but only when cruising let off and its smooth or give it a little throttle and its smooth any one have any ideas i haven't owned it long and don't know much about its past

 

First easy guess is the rear driveshaft. If it a two piece, check the carrier bearing. If it has over 75K, there is a good chance it is the Ujoints. Really hard to tell without dropping the shaft and feeling the joints for roughness. Good luck.

 

Thanks I'll start there

 

Well its not the drivetrain its all good its definitely the motor if i hold it at 1700 rpm it shakes like its missing and its a little rougher in tthe lower rpms any one have any ideas now

 

You say it's an '06? Auto or manual? If manual it could very easily be the DMF letting go.

 

Its a 06 3500 quad cab long box with a automatic it has 135000 miles on it