That is one rare gun and you really got a deal.
Not a pre model 33, that would be 3 evolutions later when the 1953 New I frame was introduced for the .22/32, 32 & 38 S&W.
Officially it's identified by collectors as a .38 S&W Ctg. Regulation Police Post war Transitional Model. They're virtually a pre war gun except for the 4 line address rollmark and the post war hammer block, (although I've seen one with the pre war hammer block).
Transitional models are few but yours is even more special, it has only one post war exterior part, the cyl release thumbpiece. It still has the barrel shaped extractor rod knob and pre war Service grips with the square cornered checkering border, lines per inch, and flat flush silver medallions.
Congrats!