It is dead obvious what happened. The weld did not have good penetration in that center bar stock that's GONE, the weld came apart, the ring gear flexed at both broken ends and eventually broke. From the looks of it, it broke on the left side first because it is a very clean break, then the piece of ring gear flung outward hitting the bellhousing and was torn loose from the right side, where it's all jagged as heck. Looks like a cheap POS converter if you ask me. Piss poor welds.
It broke.