Just bought a 2002 gmc 2500hd. Had the plow put on afterwards by lawn equip. company. Problem is this: When I drive down the road under normal conditions with plow on, the trucks temp starts to rise after about 15 minutes of driving and eventually gets close to the red zone. I stopped before it got that far. The engine is a 6000vortec. I do have to get a prep package put in but I don't think thats the problem. Do I need a larger radiator or what? - Totally stressed out.