Figured I would post the conclusion to this for those NB's who actually use the search function...

One of my motor mounts was loose. Part GX24...the two metal "L" shaped blocks that bolt to the bottom of the block.

One of the two screws that bolt to the block had backed out about 2 threads but was too tight to turn by finger...since the other screw was still tight, on the bench, the block seemed tight. I guess when under load everything flexed enough to chew through a small fortune in spur gears. I finally found this problem by accident when I took my engine apart for its regular cleaning.

Today I put about 25 tanks on the new spur gears...same old worn out stock MT2 aluminum pinions too. (NT16 Engine for Ref.)

I had to stop bashing today after one of the clutch bell bearings went for a poop. Spurs are still fine though...