Did a bunch of research on this, and yes the early K9 and k40 came in a carbon steel slide and alloy frame and steel frame. You can tell that this is an early slide by the lack of the dimple markings on the interior of the slide and the rear sight shape i.e. a triangle. The carbon slide model was designated as 4040.
Interesting also that my desire to have a blue slide on a stainess frame was already a limited production by Kahr and Wilson Combat way back in the turn of the century (2000)!LOL
Included here is an ad for the Wilson Custom version of the Kahr with a stainless black slide done by Birdsong with the black rubber grips.
And here is a Kahr Mark9 on auction listed as OEM original Limited edition with black slide and stainless frame and wood grips:
