S&W sent out a notice to LE armorers in the early 80s advising removal of the trigger stop. The stop was adjustable by a small screw that held it in place. There were a few instances of the screw working loose and allowing the stop to protrude enough that a full trigger stroke wasn't possible thus preventing the revolver from firing. We were instructed to pull the side plate and remove the screw and stop. S&W shipped revolvers with out the trigger stop after that.

Regarding the all stainless sights, my first PD issued Model 66 was a very early gun and I managed to shoot several "possibles" on the old Tactical Revolver Course in spite of the sights. This included eighteen rounds from the fifty yard line.

I didn't buy that gun when the PD traded them in and I've kicked myself since. You found a keeper, congratulations.