Tombo,
from that index that I mentioned, here is one of the pages for your radio:
http://chevy.oldcarmanualproject.com/radios/51rs38.htmThere are actually two models that were the same, except for the dial for GMC and Chev Trucks. The first model went from 1947 to somewhere around 1950 and then the second model went to 1953. They look very similar, almost identical from the front and can be used interchangeably. The earlier radio has a back that has sides cut on an angle and the later one has a straight back. The circuits are very similar but there are some subtle differences.
If you tell me which style you have I will Email you the correct manual pages.
It was quite common for the power portion of the switch to burn out on these radios first. Sometimes you can get away with hooking the radio up to the half that controls the dial light. Sometimes however the burning out of the first portion makes the switch mechanically unstable.
Fred
