[DreemKiller]

Backstory: my car spent some time in England. During that time, there was some freelance electrical work on it, and there are some British relays in the driver side door. The system has stopped working, and I'd like to rebuild the system, using original wiring harnesses and non-British parts.
When I look in the catalogs, there's a part (14512B - Replay-Power Seat or Window 56/7 Replacement - 4 terminal) that I don't see in any of the wiring or installation diagrams for the windows in the Electrical Equipment Installation Manual.
Looking in the Illustrations Catalog, the only illustration for power windows is labeled "1954/56 'Typical' Electrical Window Regulator", which is an illustration for a sedan. This illustration has the suspect relay in at least 3 of the doors. It's not clear if it's in the drivers door.

Now for my question: do I need this part? If so, will it fit into the door wiring harnesses that are available in the catalogs? Do I need one for both the driver and passenger door? What's it's purpose?

Thanks for any help you guys can give me.