I pulled the brown tank off and drained it, it didn't want to drain so I removed and blew out the petcock. I'm not sure what was in it since the tank is clean as a whistle. It's got a tiny bit of fuel residue but no rust at all. I'll be saving it for the old K2.
I've begun another shopping list, I need an oil cap, tires and shock nuts. My soda blaster caused a massive dust spot on our new vinyl siding. I had to hand wash it, I'm considering trying a hybrid wet blaster, maybe even building a cabinet.