Quite possibly, this is the most sought-after Air Chief radio out there. This radio was shown at the 1939 World's Fair, and came in brown, white (painted brown bakelite), and white plaskon. These sets are popular and can easily bring over $300.
My copy is unrestored and quite rough. It has multiple paint chips, which I haven't fixed yet. This radio bears an uncanny resemblence to the Stewart Warner Varsity series radios, it appears to me that they share the same chassis. Knowing that Stewart Warner supplied some Firestone radios, it seems likely, then, that this is a Stewart Warner design.