Poorboy, you nailed it, too much penetration and you have a very nice warped housing, too little ,and you get to post on Moparts.

Its also the perfect storm for warpage, all the welding on one side only of a tube , and with a thicker piece of steel that needs more heat then base metal for welding

The weld IMO should have been wrapped around the perch ends, and I suspect this weld failure was visible upon close inspection over time, there was a warning/

the main lesson here, check all welds, regularly, if the are important..

Nobody is perfect.

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.