Confused on ball joint reinforcement?

[66 C30]

I recently acquired an 84(I think) chevy C30 to use the front end off of. The drivers side lower control arm has some sort of plate on the bottom bolted on. The plate appears to hold the ball joint with a U bolt. I cannot find anything on this, and the other side doesn't have this part. It doesn't look like a homemade fix as the plate is fairly thick and appears to be cast. I'm thinking maybe it's a standard option on heavier trucks, C60, etc.., but can't find information on them either. Just wondering if anyone could maybe help identify this part. Thanks for the info.