No way to answer without a serial number and detailed description.
You need to call S&W
@ 1976
No difference. CTG is the abbreviation for cartridge. A revolver marked 38 Special CTG, or .38 S&W Special CTG is simply indicating that it is chambered for a .38 Special cartridge. This IS different from .38 S&W, and older, shorter, fatter, less powerful cartridge.
42-45
You will need to call S&W
Mid 1960's.
1964
Call S&W
@ 52 yrs old; 50-450 USD
Call S&W and the will tell you
@ 52 yrs old; 50-450 USD
Call S&W and they will tell you.