1969 Black 300 Deluxe SS Post Sedan

[Mr70]

RPO B-22 is an interior inner door panel ornament.It is not SS specific.
The 1968-73 Chevrolet A-bodies used it followed by "SS 396" or "SS" on their buildsheets if they were Super Sports...It was used on other GM cars as well to denote a special door panel badge,for whatever the car was,Chevelle,Malibu,Monte Carlo,Super Sport etc.throughout the years to callout their special option package.
That code was & is still being used on other GM Cars today for the same reason.
I only show Canada reporting the RPO B-22 code as early as 1972 on their Documents.