The 36 and the 36-1 were produced simultaneously. The 36-1 is a 3" heavy barrel. As for the pinned barrel, Smith & Wesson was notorious for using up all the parts on hand during engineering changes. I don't know this for sure, but it's possible that a pinned barrel could still have been produced and sent out with a 1983 serial number. Your pistol is correct, and was probably shipped in late 1982.

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