8 3/4 goes boom

I bought my 340 duster/4 speed in 1981 with a schaefer 5.38 gear set with 3 teeth broken off the 8.75 ring gear. the sure grip had cracked gears, set up with a spool and 5.13 gears and new bearings-$600. narrowed it for 11" wide tires with C body axles, $250, snapped the driver side axle end off on 3rd pass first time to Epping. new race axles and bearings-$400. 2014-on the street 3 teeth off the ring gear and the driver side axle twisted and bent-replacement cost-$500. GO 35 spline Dana 60