Attachment of clutch bellcrank bracket

[motorhead428]

My GT500 frame has three hole in the area that the Clutch Bellcrank bracket attach's. I assume that the front (most forward) two are for the bracket and what if anything attaches to the rear hole? Also the third hole (rear) is a hex with a drop in slug with 3/8th -16 thread. Have other Mustang had a similar hex slug ?The front two holes have something similar to a rivnut 3/8th-16 thread they appear to be factory. The middle hole's thread's were striped, my son came up with the idea that once we removed the original rivnut that we could tack weld a flanged 3/8th nut upside down. Should make a nice repair.