I may be all wet, but I don't believe the S&W top break actions were ever offered in 38 special. You may be thinking of the .38 double action and Safety Hammerless series of S&W top breaks. They were chambered in the shorter 38 S&W. This same cartridge was chambered in the 5 shot I/J frame Regulation Police and Terrier revolvers and in the K frame lend lease revolvers sent to the British and her commonwealth countries during WWII. These were later made as the Model 11.
The top breaks are a horse of a different color as far as frame size goes. I think the .38 DA and hammerless versions are a little smaller than the J frame RB hand ejector.
The larger top breaks, such as the model 3, are larger framed. Hopefully others will chime in here.
John