49 or 50 Ford dash knobs, I don't remember which. This car has them, even the key is cut down so it has one on it. Even the window cranks have them. This is in a 40 Chevy Coupe, been in it since the 50's.
Oops....now I remember the 51s had black plastic knobs. Danny is right...1950 Ford. 49s were plain chrome without the 4 little "ears" on the knob.
That's an aftermarket Hollywood Accessories 49 Ford radio knob. The factory knobs had a slip on locking clip inside instead of the H/A aftermarket knobs that had the set screw. The other non radio knobs for the exception of the wiper knob were smooth like the NOS ones pictured here, only the radio knobs and wiper knob had the finn's because they needed to be turned instead of pulled. These were very popular in Hot Rods & Customs. The factory knobs were an instant hit for Hot Rodders as soon as they saw them in 49 and were hard to get from Ford so Hollywood Accessories decided to make them. Sent from my SM-N960U using The H.A.M.B. mobile app
To build a little on Headhunter's correct information, there were two kinds of radios in '49; the knob shown in the OP is for the cheapie (6-tube?) radio, the more deluxe (8-tube?) knobs were cylindrical and larger.
50 Ford dash knob. Used to have one of the cars, 2 door Custom Sent from my iPhone using The H.A.M.B. mobile app