I hadn't seen a partridge sight on one either but I did buy a model 19 nickel in the presentation box that came with a partridge sight and I had it changed out to a ramp sight with I first got it back around 1979 or so. I can't remember if I kept the old sight or the gunsmith kept it. Would be nice to trade the one off the model 66 for the one on the model 19! I also picked up this model 66-2 at my law enforcement supplier, it was broken. It was a police department trade-in and someone had put a new sear in it but didn't bother to fit it correctly. My instructor at Murray State College would be proud, I was able to fix it in short order and it works great. I even replaced the rear sight blade since it had been dropped at some point. Rough duty I guess?