New here. Wiring problem

[T.Huck]

Hi!
I'm T.Huck, and I'm in West Texas. I have owned a '65 GMC 3/4 ton flatbed truck since the early 90's. It had the old V6 motor, and my daughter blew it up in 2001. I put a 350 V8 in it, from a '69 Chevelle, that had around 100.000 miles on it. My son then started driving it and had it for a few years. he then threw a piston rod thru the oil pan. The old truck sat at my ex-father in law's farm for about 10 years until I got it a few months ago and started making a rat rod out of it. I had another 350 from a '71 Corvette, and have installed it in the truck and am about ready to start it up. I have one problem.

I am doing this on a shoestring budget, and have done pretty good so far, but have spent a bit of change on a couple things, such as a generator to alternator conversion, and some wiring. I ordered an engine harness from a classic truck dealer, and made a mistake and ordered the one for a Chevy instead of a GMC. The harness plugs into a socket on the drivers side firewall goes along the fender, to the front radiator grille area. there is a plug in to the headlights, and a plug for the horn relay, and in this is my problem. The harness has a two wire plug that goes to the relay, and a seperate thick red wire that has a spade connector that goes onto a screw post, and the existing horn relay only has a three wire plug. I purchased a new horn relay for a Chevrolet truck, thinking that I would just use it, but it is quite different in that it has two screw terminals. I have looked up diagrams on line and just became confused, as they all reference a voltage regulator.

Has anyone here had the same trouble, or know haw to deal with this issue? I do not wish to invest in another harness if I don't have to.....


Thanks!