Lincoln and Mercury used the Hydra Pack type hydraulics for windows, seats, and tops in that time frame. The shuttle valves were on each actuator and the relay was fixed to the hydra pack hydraulic pump assembly. The pump assembly was mounted near the firewall toe board and the inner fender apron on the right side in earlier cars then on the left side in the later cars. It's down in there where it makes a cramped area to get to the dimmer switch and brake light wiring. I've never seen a factory mounted relay in the location in question. Folks will mount all sorts of stuff to their cars.