My old red D-50 sat for a couple of years before I put the turbo motor in. That stuff required about 10 cans of injector cleaner and about a pint of acetone to clear out the filter/sock/pump/injectors. Smelled like varnish. Gummed stuff up like tar. No bad smell, I'd just use it. I'd probably put whatever fresh gas it would hold in on top of it to dilute it some.

Didn't you guys ever just rock the truck to mix the fuel? That's how you get a "water in the gas" to fire off...

Not responsible for advice not taken...