The 292 HD exhaust manifold and 250 integrated exhaust manifold may not be precisely in the same position, but they are going to be pretty close, probably a fraction of an inch in any direction. So I can get an exhaust for my integrated exhaust, and when I finally can afford to swap the entire top end out, the exhaust pipe will be close enough to be wriggled into place and bolted up. At least enough to get it back to the shop and have them make some mods to fit exactly. I can't do that with the Langdon manifolds or Clifford shorty headers, and I'm not sure they flow significantly better than the 292 HD manifold. Being on an extremely tight budget; with the 292 manifold $169.95, Langdon manifolds for $277 with $30 for manifold heat, and the Clifford shorty headers for $359; you can't beat the 292 manifold.
My shop said if it comes in without a converter, they don't need to put one on. Since I'm doing this on an extreme budget, I can't justify adding a catalytic converter when I can just put a straight exhaust on it. So no converter.
Looking at the exhaust charts for both the regular 350/305 and Z28 350/305 head pipes are both 40471, which is a 2" pipe. The Z28 Y pipe part 42537 appears to be 2" on the resonator end, but I don't know if it is bigger than 2" on the catalytic converter end. Given it is a 2" pipe going into the converter, It's probably 2" coming out of the cat. So the Z28 exhaust will fit both the standard V8s and might fit the L6 catalytic converters as a bolt on. It looks like from the parts chart that the Z28 is only 2.25" on the tailpipes from the resonators on back.
