Broadcast sheet sales codes are alpha - numeric, so here are broadcast sheet examples showing sales codes C55, C93 & A93 from a 1971 broadcast sheet;
The codes can indicate certain sub-assemblies like front brakes, foot pedals, steering columns, rear axles, etc. Or they indicate the last two or three digits of a part number such as torsion bars. Or they are administrative codes such as Y codes.
Different numbers and letters mean different things depending on what part of the sheet you're talking about....