Any unusual sensations when up or downshifting when let clutch out, or does your quote of no shifting issues cover this?

Any shudder stsrting out in 2nd gear.

Assume transmission mount ok as you have removed it several times.

Does sound like plain old ordinary clutch chatter caused by defective clutch or flywheel surface or motor mounts. Pilot bearing fit of trans mainshaft ok?

What happens when in reverse? If nothing, would suspect again engine or transmission mounts

Don't suppose rear axle posi could cause this???