In those days, it seems more a process of running changes than new model. In my opinion, the first "transition" was the elimination of the hand and cylinder stop slots. In reviewing my few examples, I see that 8" 2nd model #1355 is also two pin with Model of '91 markings. I can see no indication of sleeving on either one (fairly obvious on my 3rd model Pope).
I finally noticed for the first time that my 1st model (6" nickel #22772, matching # frame, barrel, latch) has the hand and cylinder stop installed. Does this suggest that it was once part of a set? If so, should I letter it on the assumption that a pistol that was once part of a set is worth more than one that wasn't? Or was more likely to have been bought by a person of interest?

Bob