379 Peterbilt vibrations while under a pull & letting off throttle

I have a 2006 379 peterbilt exd. It has a cat c-15 with a eaton 18 speed & 366 rears. The motor had a complete in frame done 300,000 miles ago by caterpillar. I’m lost here and don’t know where to turn with this vibration during a pull up hill or every time I let off the throttle to shift or anything.
I recently put a new heavy duty clutch in it , a new output shaft, shaft bearing, rear seal, new yokes and universal joints all through the drive line as well as a carrier bearing and changed all the trans and rear diff fluids. Still have the noise and vibration. Please help

 

I’ve checked the cab mounts and they seem to be in pretty good shape

 

I don’t believe they did change the crankshaft dampener. How often do they go bad?

 

It started all of this before I did this long list of work.

 

Update, the truck doesn’t seem to do it when I slip it into neutral going down the road