I bought the Flowtech 31500 headers (even though they are not listed for the '65 and earlier trucks). They are ceramic coated and are quite nice. They have a thick flange and fit my 1965 K20quite nicely. The only problem is getting them in place to bolt them up. You have to make sure the motor mounts and frame towers are out of the way, the clutch linkage has to be removed (if a manual trans), the dipstick needs to be removed, and that pretty much does it. It is a tight fit, but they do work and are really nice for the money. If I had to do it again though, manifolds, but for now, a really nice set of headers will keep me company for a while.
