Never heard of center dumps (atleast have never seen any). We just used a set of "full size Chevy Pickup V6 exhaust manifolds" because they tuck in tighter to the engine (better frame clearance) than the S-10 type, which extend out almost over the top of the frame.
I bought the exhaust flanges from you a while ago, but I cant seem to find the time to make the headers. So I'm looking to take the easy way and buy the manifolds. If I can't find them soon I'm making the headers.
The "auto recyclers" around here have no idea what a exhaust manifold is let alone find one with a center dump. Mabye becouse it's made out of metal not plastic.