when i retired in 1999, we prob had close to 2k deputies and i don't know how many model 66's were still in service. since yours is in good condition and locks up well, it definitely is not my old gun. working around prisoners a good part of the time, i constantly secured my weapon in gun lockers at various jails and such, so mine had a lot of external wear and the timing wasn't spot on.
in 1974 when i was working at another agency where we could carry our own weapons, i paid a premium for a 4" model 66 from a retail dealer. i think they were selling for around $250 and i paid close to 300 or more as model 66's were really hard to find. at that time in my area, they were the gun to have. so hang on to yours as they are really nice weapons.
ed