My first post to the list: There were at least two models of the shifter.
The earlier (70s?) had the "S" stamped/forged on a solid lever, and the later
model (that was ubiquitous in the 1980s pro peloton) was cutout and smooth.
IMHO, it not only worked far better than a NR shifter, but the lever felt
great, too. That second generation model, with Spidel (the French
pseudo-gruppo) etched on it, came on my 1982 PXN-10. The bike hanging behind
me (a 1986 Razesa) has a set marked Simplex, and I think Mavic used it in
their group, too. Hope that helps.
-Ed Kasper
Detroit MI