Figured while I'm playing around with dashes, I'd start a thread going over a lot of the frequently asked questions, or things that I feel like might be useful in the future to some folks.
Just for a beginners reference, here is the backside view of a 1975 Beauville dash so you can see the common placement of parts for the early 70s models. I know they moved the ignition switch to the steering column at some point, but not exactly sure when, as my 82 has a column switch.
The first one is a question I've been asked numerous times over the years on 67+ trucks and vans, and they're both the same. I'm sure the trucks changed sometime in the late 80's or early 90's, but I'm almost certain my 91 G10 was the same. How to remove the headlight switch knob. To remove that pesky knob, you have to reach around behind the dash and feel for a spring loaded button.
It's usually facing away from the instrument cluster toward the driver's door, but could be in other locations I guess in different years. Once you've found the magic button, you simply push the knob in a little, pull it out a little, and shake it all about as you're pushing on the spring loaded button at the same time until you feel that button depress all the way in, then you can slide the headlight knob and shaft out of position and remove the switch.
In this pic you would be looking at the rear of the dash from the engine compartment side.
After you've removed the knob and shaft from the switch, you should have a 5/8 nut holding the switch to the dash. Simply remove the nut from the front, and pull the switch out the back.
For anyone that might have rear A/C, that knob just pulls off and you should have a 5/8 nut holding the switch in place as well. You should be able to just pull the switch out the rear after taking the nut off, but since this donor dash was melted, I couldn't tell if there were once plastic tabs there or not.
I'll see what other things I can discuss about the dash here in a couple days when the weather permits me to go out and get more pictures and ideas.