Occasional driveline clunk 94 mack

Just had an occasional clunk start in my 94 Mack with Eaton super 10 and Mack rears. When it does it it’s a consistent clunk every second or so and only does it under partial throttle. Goes away at no throttle or full power. Not sure what can be checked externally but don’t see bolts in flywheel housing missing or loose and throw out bearing, input shaft etc. appear fine what I can see. It really sounds like something in transmission area causing the sound but won’t rule out anything in driveshaft or rear ends. All u joints and driveline bearings feel fine. One thing I wondered is I recently had 4 new drive tires out on rear axle and front drive axle has used tires. Could there be enough of a height difference there to cause an issue? I also drained a little oil out of transmission and didn’t see any filings or chunks of metal. Anything else that could be checked?