What denotes the C/10 vs Custom/10 emblems

[special-K]

SPID is the option sheet on the glovebox door.I never called it that until I realized I was about the only one here that called it the VIN-specs sheet,which is what all my longtimer buddies always called it.I`m took GM books refer to it as a SPID(special parts ID?).
I`d guess yours is a CustomDeluxe,based on the rubber mat and trimmed glass.You prolly don`t have a headliner and the door panels have chrome trim around scrolled pattern.If you have the SPID still there,it may say full foam seat.Your seat would have been covered with a cloth insert that that is same color as vinyl with a lacey pattern.The dash knobs and pedals have trim.
I see you have "Custom" door panels.I wonder what`s original and what`s changed.I don`t know why someone would change the door panels.