Straight Six Exhaust Manifold - IMCO

Need an exhaust manifold and see them listed with and with out 'IMCO'. What is this?

 

There were two ways to improve emissions on cars. the IMCO cars used IMproved COmbustion to aid with emissions. And the other's used the smog pump to help, i think the non-IMCO manifolds had a tube to hook it up to the smog pump...but im not sure.

 

yup, ur correct.... except for the early cars that had neither

 

How early are the early cars that had neither, and/or how do you tell the IMCO manifolds apart?

Thanks yall.

 

Also - Any ideas how in the world this happened? Common or am I just lucky?

 

Its common. That part will burn out. If you need another one I have one. PM me.