Diff noise or drive shaft noise?

[FireFight]

I'm trying to trouble shoot this grinding/whining/"wha-wha-wha-wha" sound coming from under my 318i, it's clearly drive train because it only makes it when the car is moving.
During acceleration it more of a "wha-wha-wha-wha" sound like the drive shaft is out if balance, but when I let off the throttle/toss is out of gear/put in the clutch the grinding whining sounds starts and slowly goes away until I come to a spot.
Any way I can rule one rule one out that I'm not thinking of?

[TobyB]

Center bearing?

t

[FireFight]

Just replaced
As well as the diff fluid, which I didn't see any metal shards in there.

No change in noise level

[redlightpete]

Maybe put it on jackstands and have a listen.

[jeffnhiscars]

Im guessing drive shaft. You could have installed it out 180 degrees, you may not have properly preloaded the CSB causing premature failure (depends on how long ago), you could have a bad ujoint or all of the above

[FireFight]

I'm getting a new-to-me drive shaft today to see if that solves my issues.
I'm hoping so, its pretty annoying to have people stare at my POS because the sound not the ugly factor