Just to be clear, my specific reason for doing a popular "Remote Ford Relay Trick" is not to replace your relay or to say you need a relay. It is a procedure to help a heat soak situation I described. My specific install includes making a jumper at the starter terminals. It has nothing to do with your "problem".
Several of us have addressed your problem by stating that you do not need a relay for a 1955.2 GMC stock starter. I believe the relay should be omitted, truck wired per 55.2 diagram and then see what happens. If no luck, proceed to test components and wiring. I have the 55.2 GMC wiring diagram if you need help.
Sorry for the confusion, but Jerry's mentioning of the Ford
relay made me mention the little trick I've done. I make the jumper from a piece of flattened copper tubing. The reason for the Ford relay is it is cheap, available, allows for easy attachment of remote starter switch, no live cable to starter, no small wires to starter, convenient attachment point for battery hot, eliminates the heat soak issues and burnt wires on V8's. It's mounting flanges need to touch bare metal.
All this does is make your starter system like 60's, 70's and 80's Ford starters. Call it the "one wire" starter.
