AWD Astro Van TC or rear end noise?

I have a 1993 Astro AWD that I recently took on a long trip. Driving on the interstate with the cruise set I noticed a growling noise
and vibration when going up or down a hill. Not when cruising flat, not even when taking off, just on slight accell and decell. It seemed to be coming from the rear the vehicle. From what Ive read on Google the symtoms point to a bad pinion bearing. But today I got under the van and noticed there is a considerable amount of side to side play in the driveshaft at the rear of the transfer case. There is no play anywhere else in the driveline that I could tell. Would a bad bearing in the rear output of the TC cause this noise? And how hard is this to fix?
Thanks, Stephen
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