I'm figuring it's my u-joints but I want some opinions, if I go past 60 and let off the gas I get this vibration that shake the whole truck. It won't do it till I let off or I get to exactly 70-73 mph. Kinda not looking forward to anoth fix but I love my truck. Just give me some inputs. Thanks truck guys

 

i had the same problem, thought my u joints were going, checked them and they were fine, but when i crawled underneath it turned out one my rear cross member tranny mounts had back off a little and solved my issues once i re tightened it up

 

whats your definition of backed up and can iget a pic of the rear mounts

 

2wd? 4wd? regular cab? extdnded cab? auto? manual?

easiest way is to go under the truck and check for play in the u-joint. If this an extended cab truck, could be the carried bearing. It also could be the pinion bearing.

 

Extended 4x4.

 

Automatic