I beleve the Triplelock or .44 Hand Ejector 1st Model is the first N, coming out in 1907. It was supplanted by the Second Model which did not have the crane lock or shrouded ejector rod in 1915. The shrouded rod reappeared in 1926 with the 3rd Model (Wolf & Klar) .44.
The Outsdoorsman (1931) and Heavy Duty (1930) were the first .38 N frames.
Thanks for the corrections. I don’t have my library here so I can get the ‘right’ information. Just going from memory, which I am losing rapidly. :)