Well, I guess they survive LOL....I don't really know how susceptible they are to failures there.
More guessing: If all these SBM ball/socket failures were on the driver's side, then maybe it's due to the oil distribution. The SBC has separate direct feeds to each lifter gallery via a deep groove under the rear cam bearing. The SBM has the passenger side at full pressure, but the driver's side lifter gallery is fed via a shallow 'groove' across the #1 main and that restricts flow and drops some pressure. So the driver's side SBM lifter gallery sees lower pressure, unlike the SBC where both lifter galleries see full(er) pressure.
You might help the SBM driver's side lifter gallery pressure by grinding out some of the walls between the 3 passages down to the #1 main, but you still have 2 longs passages for the oil to flow through to reach the driver's side gallery, and it is fed at the very far end of the oiling system, where pressures are naturally going to be lower. The SBC's 2 passages to the galleries are very short, and right off of the feed out of pump. It's just a better designed system in that regard.
