Ron,
Not to nit-pick, but in the referenced page there is one technical error.
That is why a lot of 122s have rust between the stainless door trim
and the door growing out from the spring clips, and also many cars from
the 60s had so much rust. On your chart you compare carbon (mild) steel
to active stainless. Since the stainless makes an oxide when exposed to
air (even without a passivation treatment) it is in the passive condition
and is thus much more noble than carbon steel. For that reason you need
to be careful about moisture accumulation where it cannot dry. A layer
of paint between is probably a pretty good idea. The steel needs to be
painted in any case.
--
George Downs Bartlesville, Heart of the USA!