S-14. As far as I can tell from my research, the AP generation had a number of Alps keyboards, with nice spherical doubleshot caps, and occasionally with SKCC switches in strange places. I want to investigate further, but I think I'll have to wait till a few more checks clearhypkx wrote: ↑From which model number are the keycaps?
The S generation appears to be the last ones before switching to some other kind of switch - The LED positions change entirely once the S generation is done, and the S series had already gone from SKCC/SKCL/Who knows what to SKCL and integrated domes.
This is mostly speculation through overanalysing images from Google, though.