My 1990 K5 never had a smog pump since I have had the truck. I dont think it came with one from the factory. Its always been a California truck. I rescently installed an engine from an 1989 K5, Colorado donor truck, and it has all of the smog equipment on it, smog pump, tubes out of the exhaust manifolds etc. Can I take all of that off and not effect anything? If my truck didnt come with it, I see no reason to keep it if I dont have too. Also, did they use different belts? The guy at the parts house said it was the same belt.... I would think the one with a smog pump would be longer??