- There is no specific RPO code for the Limiteds. They are identified by the presence of an "M" instead of a "J" at VIN position five.
- There are two types of seats. Leather cars have the AS7 split 45-45 seats with the raised center console. The cloth split bench is a separate code, which I forget at the moment. You can tell instantly if its a leather or cloth interior with these two codes.
- Colors, particularly the two leathers, are defined by more than one RPO code, relating to different interior components (seatbelts, trim, etc.). In true GM fashion, not all cars have all RPO codes that you might expect. 623 is *not* definitive for a tan leather interior, as you will see below.
Here are the pictures of my tan Limited with leather interior. Notice there is no 623 in the RPO sticker. The window sticker lists code 976 as the correct identifier. That code is also absent on the RPO sticker. Good game GM.