Maybe driveshaft, differental or transmission?? Problems...

So im having problems down under my truck, when i accelerate at any speed, it starts clicking and clonking around the drive shaft. Another example is when im at a stop and i accelarate just a little, theres a big clonk sound as if something was to move backward or something. Any ideas?
-1990 b2200 175000miles

Most likely you have a bad u-joint.

Clunking sound is typical symptom of a bad U-joint. Get underneath and see how much play there is in the drive shaft. This inspection is a lot safer when the truck is not barreling down the road at 50mph.

Could also be a bad center carrier bearing (support)