1986 GMC Astro rebuild...questions

Haha...so with that note check this out!

 

Or this one! LOL!

 

Here is the air dryer off the truck now. The farther I look in this truck, it sure seems to have taken a real beating with the elements. Yes I've seen where there some pretty cheap new models--likely I'll get one but the tinkerer in me will have to take this one down and get a deeper look into it. Last truck I had I was able to make it's dryer work again...

 

Back to the tanks/fuel issue again:
I've drained off some fuel from bottom outlet of the passenger side tank to nearly dry, but then moved the truck just a few feet to level it up. Of course in doing this, more fuel moved into that tank. So maybe about 3 inches or less level now in both tanks...
From what I can tell, the only connections to the passenger side tank are the crossover pipe (again, no shutoffs/valves on it) and one line connected at the top of the tank, that looks to be a pipe going down to very close to the bottom of the tank, just about at the edge of the crossover tube outlet/inlet.
I'm trying to learn flow routes, connection purposes, and the do's and don'ts. SO, if I drain the fuel completely from both tanks, will this then enable air into the system, even though it's not running? And after cleaning the bottoms of these emptied tanks and adding new fuel, wouldn't I have to go about some bleeding processes?

 

Disassembly started...

 

A little deeper...a little concerned though..imprint on top of canister says "high spring pressure do not disassemble"...doesn't this canister screw out as a unit?

 

A little more...now off to work on my train--customers waiting on their cars so we can all serve the world...