The reason I ask is that my intake has a casting number of C6AE 9425 G and Mansfield Mustang states I need the C5 outlet/thermostat housing. Bob, if I understand you correctly, I will need the larger thermostat and the smaller C7 outlet. It does look like the recess in the housing could seat the larger thermostat flange. I apologize for my ignorance, but don't have any parts to compare or experience...yet. All I have is my MPC, Osbourne and shop manuals and you guys...along with a bunch of patched together pieces I am trying to figure out. It seems that a 67 was probably not the ideal model year to begin learning, with all of the changes.