I'm in the same boat. Tried some stainless S-10 swap shorties (ebay), outlets positioned well, passenger tubes covered the spark plugs. Was going to send them back but USPS wanted $68 cost of headers was around $110 sold for $100. Trying cast manifolds (el cheapo) 1 issue on passenger side, really close to rear lower control arm bracket, hopeful that my exhaust guy can clear that bracket. 6.0 4l80 swap using adapter plates for clamshell mounts & of course had to loosen mounts on crossmember for the clamshells would line up.Truck manifolds, flanges are turned, so they hit the frame.C5 manifolds don't work, won't clear crossmember. Incomplete,one bug at a time.