I have three safety bars from SW revos and don't know why they are all different. I believe they came from:
60's era Model 10 (K frame)
90's era model 686 plus (L frame)
after 2000 (MIM) model 66 (K frame)
I would have thought the L frame one would have to be longer? AFAIK, none have been modified even though the middle one has a curved notch in the head.
Anybody know just by looking which is which?