Metal Intake Gasket

2 Darts said
For iron to iron and a metal gasket, I use a skim of red RTV around the ports. FWIW: I have not had good results using a metal gasket with an aluminum intake. I've used a thicker intake gasket, again with RTV red.

Exactly.

The steel gasket if for the cast iron intakes.

If you are installing aluminum, go with composite/permatorque style. Do not use the metal gasket with the aluminum intake.