[LarryFS]

There were two chassis used in the Silvertone Model 4663.  Nostalgiaair and Rider's both have schematics of chassis 101.471 made by Colonial.  My 4663 has chassis 100.158 made by Stewart Warner.  The only place I've heard of to get that schematic is from the inside of the cabinet.  As you saw, my cabinet schematic is incomplete.

I will have to draw the circuits associated with the 5Y4 as this radio now has them and see if I can understand what has been done to it.