"Pump rub" is new to me. Never heard of it before. I can't comment on "pump rub" beyond that.
The entire output side of the gear train would be stationary, the driveshafts/U-joints would be stationary, the differentials would be stationary. I suppose the input side of the transfer case could be rotating. So a problem on the input side--failing bearing or thrust washer, for example--might be noisy.
I think you're mis-diagnosing a vibration from something else--an exhaust heat shield, the flexplate, the serpentine belt/tensioner...and getting caught-up in "transfer case" when the problem is somewhere else.
But I've been wrong before, and I'm not there to inspect it.