The S&W J frame was designed to take the extra length of the 38 Special Cartridge in the S&W Small frame revolvers and was first introduced around 1952. Be fore this if you wanted a small frame 38 it came only in the 38 S&W also known as .38 Short & Whimpy. The J became so popular that in 1961 all early I frame guns were given the J frame.
A pre model 36 3" 38 Special Probably made around 1955.
A 22/32 kit gun model 34-1 made around 1965 Prior to 1961 these had the smaller I frame.