It is a three screw M36, case hardened trigger and hammer, flat latch, diamond walnut grips, square butt, five numeral serial number (no letters). 4 inch pinned tapered barrel with serrated ramp front and gutter rear. Most likley professionally reblued. ONLY markings are deep serial number on butt, deep ".38 SPECIAL" on right side of barrel (hense Rossi hunch) and lighter "rack number" where my other 3" and 2" M36s have the four lines starting "MADE IN..." Barrel looks like a longer version of my 2" 3" M68 Rossi's (same rib and sight). BUT those are marked "AMADEO ROSSI..." on left side of barrel. The only thing that says S&W is the medalions on the grips.
Theory 1: Barrel swap and shallow markings pollished off before gun was reblued (but why is there a rack number just below cylinder just forward of sideplate?) Theory 2: Extra from some sort of special order foreign sale, maybe somewher that made in USA isn't a selling point? (But my other M36s say ".38 S&W SPECIAL CTG." ?????