The headers I ordered have arrived, they are intended for a late model four weel drive Chevy truck. They fit like a glove, with literally not much room at all to spare. I am pretty pleased with the way they fit, though I wish they had typical 3″ collectors, though if they were such equipped they might not actually fit. They are intended as direct replacements for the factory restrictive manifolds and as such have a 2″ collector. Which despite not being optimal, will be sufficient for now as this engine is mostly stock. However, when the new engine is installed, these will be replaced with a custom built set using 1 7/8″ primaries and 3.5″ collectors.
These current headers will be adapted to a 2.5″ dual exhaust that breathes through two Flowmaster 40 series mufflers and will exit right before the back wheels on each side. The design of the exhaust system will allow me to remove these headers, and build the new set down to meet up with the existing system.
Below are some photos that show just how tight of a fit it is using out of the box headers.