movingforward: Your Highway Patrolman (Model 28) dates from 1974-77, and you are correct that the ".357 CTG" simply means that it is chambered for the .357 Magnum cartridge (like all .357s, it will also shoot .38 Special). S&W does not use a transfer bar in its revolvers - your revolver is equipped with a hammer block, which was developed in 1944 and is standard on all S&W revolvers made since that time. It works something like a transfer bar in reverse, preventing the hammer and firing pin from contacting the cartridge unless the trigger is held to the rear.
Centaurus: Your Model 38 dates from the 1971-1972 "wandering J" period when the "J" in the SN of 38s and a few other models appeared in different places with little apparent rhyme or reason. The first Model 38 rated for +P was the 38-3 in 1997, so you don't want to be using it in yours.