the ones I got are of course an aftermarket performance header that were built to fit the 88- 95 chevy trucks with a 305 or a 350 engine. It did not say whether for a half or a 3/4 ton or even if it would matter. I am by the way using a different chassis now so this idea may not work for everyone but I thought id share the idea with you guys out there. ill take some pics and get them posted. these are easily found for under 200 on ebay. I pretty much knew my trouble areas trying to fit other headers then saw these and saw no reason they would'nt work for me. All of the performance parts catalogs offer similar as well.