[Keith True]

I have some of those I installed on my truck.I just assumed they were a backyard fix,and if they're done properly,I like to use any old things like that I come across.Mine were not riveted though,they're welded.Mine have cracks that were been welded like yours too.By the looks of yours,I would say they were welded without the reinforcement in place.I can't see them being welded years ago without the weld melting into be backer at some point at least.A close look at the rivets look like they are more home brew than factory too.With all the aftermarket stuff there was back then those could have been a repair patch sold by Western Auto or the like.I have some weld on rear spring perches that were sold back then.You sliced the original off the axle housing,ground a bevel on it,and welded another one on in it's place.I vote for a well done dooryard fix.