The N2xxxxx serial numbers ran from 1974 to 1977.
I-frame 32swl, serial 4544XX
It would be a 32 Hand Ejector 3rd Model. Serial numbers ran from 263001 in 1911 to 536684 in 1940.
Heat treating started at SN 321000 in 1920. That's as far as the book breaks it down.