I haven't taken them apart, so I don't know for sure, but I believe that they are very similar if not identical. I seem to recall that the 2s are supposed to have some improvements over the 1s. I have three sets of Silver 2s at the moment, and they all seem to be different in terms of feel. One set is fairly stiff and another will rotate with zero effort. The ratchet mechanisms of the 1s and 2s are the same from outward appearance, and the same as Dia-Compe from outward appearance. These came on my Custom, but I prefer the looks of the Silver 1s, for frame mounted. The 2s are better as thumb shifters in my mind.
Laing
Delray Beach FL