Chevy Pontiac Buick Oldsmobile Cadillac Ford Rear Antenna 54 55 56 57 58 59 60

Description

I got this loose and do not know anything about it.
Stamped on the bottom of the chrome bezel is C8109 R. Something LEX.
I think this is a rear antenna.
Please confirm application before buying.
The cars in the title are only guesses.
Chrome bezel has some pitting.
Antenna extends and seems to work well, but shows use.
I guess there is some sort of chrome cap that is supposed to go on the top, but there is only a nut.