I have a 2000 durango with 102,000 miles on it. When accelerating slowly a
squeaking noise is heard, when foot off pedal, sound goes away. At freeway
speeds, the noise also a noise that seems to be a low tone (bass) fast
repetion viberation when the pedal is pressed down and it goes away when
pedal is released. Sounds like noise from deep tread on tires/road noise,
but is consistent no mattter the pavement. Occurs at speeds greater than
45mph.

Dealership did a test drive with me and said he thought was the drive shaft.
This does not make sense to me, could he be right?

Mr.

It could be bad U joints, does it make any big clunking when doing from
drive to reverse

No noises when shifting from drive to reverse, while vehicle is stopped.
Don't think I dare attempt the shifting while moving...