I'm about to dive into my swap and I want to have all of my ducks in a row. Now I know that f-body manifolds will work as well as Trailblazer SS manifolds. My question is: has anyone used aftermarket headers for a TBSS? I have to buy manifolds either way and haven't had much luck locating used TBSS manifolds. Another question: do 5.3 Trailblazer (XL) manifolds work? or only 6.0 SS manifolds? Thanks for any input!