Will, the sights themselves are all exactly the same. On the 1st model the ears that hold the sight were machined integral with the upper tang. All the later models used the base as you have pictured. The basic tang sight was not graduated. The instructions called for the user to sight in his rifle and scratch a mark on the sight with a knife. Then go to longer range and do the same for each range they planned to shoot.

There were graduated sights available and ones with an eyepiece. There was a windage adjustable sight with side screws on the vertical slide to more accutately move the windage slide and of course there was the rack and pinion sight. There was also a Lyman sight that used the Maynard spring under the tang to lock it in the vertical position instead of the normal Lyman method.

Yeah, John.  Thanks.  Now when are we going to be able to find somebody to build a good repro of the rack and pinion sight?    I'd even be happy to find a slide with the "real" eyepiece that screws in to use on a regular slide body! 

Froggie