Thanks Jon, I'll edit the description with the correct number...AFAIK the ratcheting action is just to provide a kind of resistance similar to the Simplex retrofriction's spring, more akin to SunTour or Shimano ratcheting, but the detents in these Mavics make for a much 'coarser' feel than the fine-tooth feel of the SunTours.
I don't think there was any indexing system that these were supposed to correspond to, just a variation of standard friction and will certainly work with 6-spd gears, probably 7 and 8 too, but I haven't tried.
I should point out that the 3rd extra lever I have to trade was modified: the plate that fits on the frame boss was ground nearly flat (maybe to use on an OS frame like a Canondale) so it's a spare for parts, IMO. I didn't do the mod.