Actually the first radios for cars and trucks were built in the late 20's by a comapny called Galven.... their line of radios were called "Motor-ola's" or? as we know today the Motorola company...lol Those radios in the 1920's through the mid 30's were basicly after-market dealer add-ons, rather than factory installed.
Other companies selling these add-on radios were "auto-matic radio", Crosley,Zenith, etc. Even Firestone and Goodyear got into the act selling radios under their name(built for them by other company's).
In the mid 30's, various car/truck builders, seeing the growing popularity in the radio market began dictating the specifications for those dealer installed radios, as well as contracting to the radio mfg's to produce the radios to a specified type and style.

In the 1930's most all radios (including those installed in Chevrolet products) were mounted on the firewall of the vehicle and remote controled from a control set mounted to the bottom of the dashboard. The radios used by Chevrolet were built by "United Service Co." a division of Delco Electric. and were of the remote mount type with the control head mounted seperately under the dash. chevrolet did this until the early 1940's.
The most common style control head used by Chevrolet in the '36-'39 years was a small (approx 2in) round dial face, with the tuning/volume controls mounted to each side on the horizontal centerline. these controls were mounted to the bottom edge of the dash using a nickle plated bracket, kind of like you'd mount an underdash guage-set today.

If anyone is interested I have a control set from a '38 chev that I can photograph to show exactly how it would look.
michael
President emeritus
Puget Sound Antique Radio Assn.


\'48 chev 2-ton boom truck (Boomer)
'49 Chev 2-ton flat bed
'65 Chev 35ft school bus
'88 GMC 6500
'72 Superior 26ft class "A" coach
'50 Farmall "M"
'71 MGB GT
'68 Austin-Healey Sprite
'65 Austin-Healey Sprite
and various other odd British cars
and lots of old radios.....

Although we know what the speed of light is..... What I want to know is... How fast is the speed of DARK??