car is 10 years old with low mileage, 55,000mi.
It has a 4.44 FD and OSG diff.
Stuff I've done so far to rectify the issue are complete Mugen suspension bushes, spoon diff mount, OEM engine and tranny mounts, swapped out axles with friend and DSS alu prop shaft.

Play is especially noticeable while negotiating at parking lot at very low speed and gear. ie. 2nd gear @ 10mph.
Able to induce with quick stab of throttle at low to mid range speed. acceleration and engine braking isn't instantaneous.
Feels like uber wrong FD backlash, suspicion is mech did not change bearings when installing FD.

The sound happens is when I'm neither accelerating nor decelerating. ie. engine braking as I'm approaching a stop light with the rpm at idle speed before clutching in or maintaining speed along highway.
I would describe the sound as light rumble which you can feel it, inexperienced gut says it's pinion bearing as there is no load on the bearings at engine idle speed and considering the drive line play as well.

Will try to record sound clip and/or video tomorrow.

Eternally grateful if anyone can help.

 

clutch?

 

OEM clutch plate and ACT pro lite flywheel was installed early this year. Retained OEM PP and replaced TO bearing.