Welcome from AZ.
My '81 Custom Deluxe with a 250 had the same actuator but that was long ago and don't remember. Looks like it opens and closes a valve on the exhaust. Can't tell from the photo. Exhaust definitely.
LMC, maybe Steele Rubber. Should be several outfits that would have them. I know the gaskets for my '72 Olds mobiles are available so a squarebody is much more common.
Like I said earlier, read the owners manual. It's got a lot of good info. Hardly anyone reads them. When I buy a vehicle I'm unfamiliar with, that's the first thing I do, read the manual. It will tell you exactly what fluids to use unless it tells you to "take it to the dealer".
I agree, any maintenance makes the vehicle a little better. A wash, new belts, oil and filter even new bulbs. Some more than others, I think it's a care thing, most of it in my own mind but also mechanical..
All the small blocks I've ever owned averaged 15-40 PSI at cold idle. Depends on season and type oil as well from my experience.
283, 327, 350 and 400.
Welcome from Dolan Springs, AZ!
It reminds me of my '81 Custom Deluxe C/10, SWB I drove for 15 years as a daily driver. Mine had a 250 with 3 on the tree.
Start with the clamps on the battery posts. Make sure they're clean and tight. When things get cold and old they can contract and expand more. Also check grounds.
Welcome from NW AZ!
I've traveled through your neck of the woods several times, I like it there. The first time was back in 1985 on my motorcycle on a scenic road trip.
Sounds like a nice truck you've got there, enjoy it!
Welcome from Arizona!
Too new a rig for me to be familiar with but from my past work I think it could be your light switch that dims and brightens the dash lamps. Something to check anyway. Good luck!
Welcome from AZ!
Take it out on a highway run for a couple hundred miles to get everything working smooth again. I may be all it needs. 51,000 miles is hardly broken in.
Wow, nice pickup!
I owned an '81 Custom Deluxe SWB C/10, 250, 3 speed on the column for 11 years, it was my daily driver. Very simple and reliable. I bought mine used for $1,400 in Alaska.
Thank you for sharing the photos and welcome from northwest Arizona.
Seen that happen a few times. Sidewalls blow, tread separates, not pretty and can cause some damage. It pays to check the date code and the tires physically.
https://mohave.craigslist.org/cto/d/lake-havasu-city-1983-c20-suburban/7680016492.html
I'd check this one out if I wasn't trying to sell 2 Oldsmobiles already.