The crossovers illustrated are associated with various systems and if you know the system number (rather than the crossover number) you may find the crossover in question listed (e.g., 3133A). What I'm not seeing are the old schematics that were hand-drawn and included the crossovers also intended for consumer install or as an add-on (e.g., N1200, N2400, N7000, N8000, etc.).