Drive Shaft Click
 

Post for my brother, his truck has a clicking sound coming from the driveshaft area. The drive shaft is about a 4" tube and made from aluminum. When you put the truck into reverse and or drive there is a small click. When going down the road and putting some beans to it, you can hear the click. I'm thinking the driveshaft is twisting from the torque and I dampend the sound on the universal(s) front and rear and can hear the sound come from the middle of the shaft. The universals were replaced in hopes that was the fix as well as the yoke greased but no such luck.

Any ideas? Mostly I work on 1st gens so this is a bit new to me.