Re: Headlight relay switch

["K M" <symbiotic@hotmail.com>]

>Nope. I'm talking about the vacuum operated switch under the front
>fender, which controls vacuum to the headlight actuator diaphragm. it
>switches vacuum and atmosphere between two ports.

There are two of those on the early 74s (like mine) and then they realized 
that only one was needed so later models only have one.  The website lists 
"Dr. Rebuild" 1-800-8669 DOC P/N2771200 for a replacement or rebuild.