I have noticed my has started to bounce some in the rear end around 60-67 mph. I have taken the tire preasure down but it is still doing it. Any thoughts?

 

what do you have in the bed, where are you driving...

you may be coming up against the overload springs and expansion joints, not sure.

 

should have stated i am not towing and empty. I thought at first it was just a section of road but this morning it happpened on a dif road where i had previously not noticed it. If it is a drive shaft out of ballance or bad u joints, would it not do it all the time ?

 

i had some drive shaft issues, but they make the entire turck shake at low speeds. thought it came from the front, not rear. put a spacer on the bearing.

I also think it would do it all the time.

 

Sounds like the rear tires are out of balance. Also, check them for roundness. If they are not perfectly round some tire places can shave them round for you.