I noticed that you used the letters "AD" in the subject line. Normally I think of AD trucks as 1947 2nd series to 1953. In these years the radio instructions showed power being connected to either the ammeter or the unswitched side of the ignition switch. It leads me to believe that the ignition switch was not designed to handle the radio along with everything else, through the switch. I don't know how it was wired in 1946 but someone may have the instruction sheet.
