This is the one I made, with relays hidden down the kick panel. Didn't need to cut a wire, just remove terminals from floor dimmer switch plug and install on relays plug, and link the floor dimer switch and relays with a wire section on same color to still trigger the relay.

just needed the relays, plugs for relays, 8 packard 56/58 terminals, violet wire piece, red wire piece... 2 eyelet terminals, and red and black wires for positive and ground. Couple of fuses or even better a breaker.

It can be made also similar close to bulkhead into the cab side, just that the red and violet wires originally going to bulkhead will go to 86 terminal, and the wire piece to replace into the bulkhead will go to 87 terminal