Apparently there was an OEM ribbed pattern available on the 91's that had the same look as the ribbed Katzkin kits. I was under the impression that my seats were Katzkin recovers until I took them apart and found OEM nissan numbers stamped on the leather parts. Some claim that I've got Katzkins, other say that the ribbed look was only for the cloth seats. I did a bunch of research on it a while back and found OEM ribbed leather seats were an option (but perhaps a dealer-associated post-manufacturing install). From the accuracy of stitching in mine (the ribs vary a bit in width), I would tend to believe that they are Katzkin, but the guy I bought it from (the original owner ... a Nissan Master Tech) said that it was an OEM option that he got along with the mudflaps. Maybe the dealer had a Katzkin option that was installed if desired ... I'm not sure. Anyway, I finally decided to call it the "OEM" leather since the original owner bought it that way ... whether Nissan or Katzkin made it is still up for debate at this point.