Nice old shooter there!
I saw what was tagged as a model 10 in a gun/pawn shop case once. I looked at it, and commented that it wasn't a model 10. They said they were making their money, no problem, so I bought it. It was priced at $185 (in the 80's). It was a 38-44 heavy duty, 5", with special order adjustable rear sight (the one that's fitted very low and cleanly into the top strap), and a special order ivory bead front sight. I took it to another shop, owned by a friend that collected Smiths. His eyes lit up! He had a case of the "Wants"! It had a little holster wear, which he didn't tend to buy for his collection, but with the special order features, he was willing to overlook the minor wear. He traded me a new 586 in a 6" (when they were a new model), a holster, cartridge belt, and a box of shells.
I still think he got the best end of the deal, and regret trading it off.