For the record, Performance Bike says the Kook Stop smooth post canti pad (pure salmon one-piece, non-cartridge) is discontinued.
https://www.performancebike.com/kool...-mtcsa/p345721
Maybe they just mean discontinued by Performance.
Anyway, striking out so far finding these Kook Stops. I still have the dual compound, the KS Eagle and Jagwire as options.