hood and grill are different, but front fenders are the same except for the parking light holes in the GMCs - a GMC fender and a welder with a small disk of metal will make a chevy fender.

All of the nose clip parts are common from 1/2 ton to 1 ton and then they get bigger at 1-1/2 ton on up. Cabs are the same from 1/2 ton to 2-1/2 ton.