Why is there a Funky vibration at 52 mph?

well to test trans theory take it up to 65 or so then put truck in neutral and see if if vibrates when u hit 52.....

but would strongly suspect the vehicle's alignment way before the other causes.....especially since those years use curved tie rods and are therefore almost impossible to keep in alignment......which wears ur tires out 2-3 times faster than older straight style tie rods.....

** regulations require the bent rods for "crumpling" in accident.....

try running up to 65mph and put the truck in neutral. let it coast down through 50-55mph. if the problem goes away, i might suspect trans/converter, if not , look closely at the axles/drive shaft. tricks like these help isolate the problem.

For a start you need to have all the wheels balance to rule that out and at the same time have all the wheel bearings checked .

Sounds to me like you need a whole new truck so come on down we'll milk you for whatever you got.