Noise has gotten probably 10x louder after I got clutch replaced and flywheel resurfaced by a reputable shop. Noise appears to be coming from transmission / drive shaft area whenever foot is off the gas.
Plates will be replaced and rear diff. fluid will be drained/refilled. Will look for any chunk of metals. Will also look for loose bolts...
Considering noise has gotten 10x worse after clutch replacement, I believe noise may be related to clutch/resurfaced flywheel. Can't say for sure though.