Door Jamb Decals?

[TX '90 ZR1]

Hey Guys & Gals.
There is a 150 mile '90 for sale on BAT. The door jamb has a decal I have not seen before. It says "Preferred Customer" and a number code.
Anyone have any ideas what the significance (if any) is? Factory installed? Ideas?
Pic attached :cheers:

15942

[DRM500RUBYZR-1]

Certainly added by the selling Chevrolet Dealership.
Not typical of factory labeling.
:cheers:
Marty

[TX '90 ZR1]

Thanks Marty
I suspected it would be something to do with the dealer. Just wanted to get input from the experts here!
:cheers:

[WARP TEN]

Looks like a dealer stock number to me. Maybe in addition to the standard stock number sticker that is usually in the windshield. --Bob