Update: only 2 months on the newest swingarm and the same type of failure. With over a hundred hours of punishment I noticed a crack while doing my daily inspection. Pulled it in the shop, pulled the motor and...... the pic's pretty well tell the story!
I used much heavier steel this time and I'm still under-engineered- AGAIN!!! I'm getting pretty good with this failure!!!! I'll need to add many gussets to carry the load away from the welds.
I'm now trying to figure out why this occurs on this buggy and not on the Spiderbox- the major difference is their suspensions & of course chassis design. Back to the drawing board