The first generation of these had the infinity logo pinned to the grille cloth. (RS1) First gen also had black center caps on the woofers and the surrounds are inverted. These speakers offered in the C/L ad are NOT first gen RS1.
There were 4 further iterations of these. The second series RS1 with a fuse mounted halfway up the backside of the mid/tweeter tower and an improved crossover in comparison to the 1st gen RS1. Both first and second generation RS1 the passive crossover lettering is red. The only way to tell them apart is look for the additional fuse halfway up the mid/tweeter tower. There were some subtle mods to the second gen crossover as well, but the fuse is a dead giveaway. 2nd gen RS1 also has center caps opaque like the woofer cones, and non-inverted surrounds.
There was an RS1a on which the passive crossover has all three fuses in the crossover, and the lettering is gray.
1st generation RS1b has an additional attenuator on the crossover, and 4 fuses. The wiring to the EMIMS and EMITS is all different colors.
Last gen RS1b all wiring up the back of the mid/tweeter columns is black, and it is loomed much nicer. These are tough to find, as it was a change made in damn near the end of the run.
Regardless, if these are functional, even missing the diffraction wings, they are still IMHO regardless of generation...... worth every penny the seller is asking for them.
Paul