Left versus right application?
The left is one of the prototypes, and the right one of the early production. These long slides (which I like) must have been a carry over from military and 600 yd. + shooting. Of course the early days bullets of heavier weight were in use and I think this must have been the bulk of the influence. As bullets of lighter weight were used that much elevation is not needed. (sure makes for a bad head position). These sights look great on the early rifles!
FWIW, using the long slide set at about 125, I was able to reach the fabled white buffalo at Raton. 1153 yds if I remember correctly. I was using 220 gr cast bullets and pretty reasonable loads of 5744 (28 gr ?). I would guess that 1200 yds is about all the sight is good good for with a 24" barrel and standard front sight.
So let me get this straight. The Lyman 48 has over the years had long Long slides, Long slides, short Long slides, Middle length (?) slides, Short slides, and short Short slides?
The front sight was the original I believe
http://www.amoskeagauction.com/104/414.html
Back in the day the slide numbered to 150 was called the long slide. Newcomers have started referring to the slide numbered to 125 as a long slide as later Lyman 48 slides came numbered to only 60.