Check oil, check coolant level, check tranny level. If you put fuel stablizer in, it could be okay..
Since it's a 2006, it'll have fuel injection, so a bunch of electronics linked with that, but as long as the engine batteries are strong and it's not been infested with rodents in the engine compartment, it should fire up.
If you have 75 gallons of 2 year old gas, just go out and see how it's running and if bad, try to get thru 1/4 tank and put some fresh gas in, drive it some more, etc.. If it's driving okay off the bat, take the tank down as far as you dare and fill up with fresh stuff..
What the rest of the rig is like, is just gonna be what it is.. Check the water system by just pressuring up the system and checking for leaks. I like doing this with the water pump only and then letting it pressure up and then wait and see if the pump cycles on/off. If it does that, start looking for leaks. It could be the pump itself too, but main thing is to check for leaks.
Check the propane. Open the valve and check for leaks initially, then start firing up the stove, heater, water heater, fridge.
Pretty much what I do every Spring on my TT.. I don't have the engine to deal with, but that's just like any other truck vehicle out there and I've worked on old stuff and the like that has sat before, and as long as you can turn a wrench and know the basics of an internal combustion engine, it should all be a DIY job.
If not, bust open the wallet and hope you can find someone to fix you up.
🙂Good luck! Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.