Shakes above 50 mph.
Balanced tires and driveshaft. Checked mounts-ok.
gas/diesel?
4x2/4x4?
manual/automatic?
shaking front/back/whole truck?
engine RPM related/ truck speed related?
is it worse turning left or right?
Tire balancing spin balanced/load balanced?
We need a lot more info.
Just a guess, you have a tire with tread separation that a spin balance wouldn’t detect.
Swap tires front to back and see if that makes a differnce.
I do have one tire that was new with the truck in ‘06 on the RR. The others are about 6 years old. I don’t drive it much. I don’t see how the spin balancer wouldn’t pick it up, but maybe. I could put the spare on and try it.
It’s not horrendous. Just enough to annoy you. Sometimes worse than others. Above about 50 or so.
Thanks