Not a lot is written about the 58. A fixed rear sight version of the 57, with no ejector rod shroud. Limited lifetime production of the original of just over 20,000. Introduced in 1964, along with the .41Mag cartridge, and discontinued '77. Then re-inroduced recently in their "classics" line of revolvers. The original stocks were skinny with a diamond which was dropped for plain stocks later. S&W shipped so many variations at dealer requests, it's hard to know whether some stocks are original or replacements, especially since you can swap any "K" frame square butt stocks among models.
If you'll give me the first 4 digits of the S/N and I'll see if "The Book" has a date for you.
Very nice. Even Jeff Cooper, Mr 1911, thought the caliber/gun combination was a good defensive tool.