1985 GMC Cruise Wiring
 

I recently purchased an '85 GMC Sierra Classic 3500. The cruise servo diaphram had been removed because it was bad but the owner gave me a good one along with the truck. The servo has a spot for a flat 5 prong plug to connect it. At the firewall approx where the servo goes is only a small square plug with six holes, five of which have contacts in them. Is there an adaptor plug to go between this plug and the servo or am I looking at the wrong plug all together?