Theoretically, if you have 2 Model 27-2's blued with 3.5" barrels in the same condition (97%+) one is an "S" series(1966) and one is an "N" series (1977) is there any difference in price? Just asking.
I think the biggest difference would be the diamond Magnas on the S series gun made before about 1967. In my mind, they add around $100 to the package.