Your radio is in Rider Vol #10 so 1938 is the proper year. A schematic can be found at:
http://ww3.nostalgiaair.org/schematics/STW/_STW_10-9.gif
Advance the page number from 10-9 to 10-10 etc. There may be more information about your radio. Wait 30 seconds between page selections.
Norm
:I have recently acquired a Stewart-Warner 91-51 tabletop model and looking for information about it. I think it was made in 1938, but want to know more about it. I can't seem to find this model in the books I have looked in. Is this model somewhat rare?