Was surfing gun broker today and there is...
It helps to give the auction number so we can look at the purty pichers too.
But I found it:
Somebody has already told the seller that a Model 58 is not stainless, that he likely has a plated finish. But not a bad job.
If you look at the third picture down, with the cylinder open to show a fuzzy stamp that I assume reads Model 58, you can see that the barrel top rib does not match up with the frame receiver ring and topstrap.
The fourth picture shows a non-recessed cylinder. Weren't all M58s P&R? The barrel is pinned but the cylinder is not recessed.
I haven't seen a S&W of that vintage with a sight blade simply dovetailed into the rib, either.
It sure looks like a gunsmith job to me. ("Previously owned by a gunsmith" might be a clue.)
Not a bad looking gunsmith job, but if I wanted a fixed sight .44 magnum, I would want a close examination and testfire before I paid my money.