So it wasn't the solenoid or battery, it was the starter. It was working fine for the most part over the last 2 weeks, but the "delayed crank" would sometimes come up. But one day it just wouldn't crank at all. Starter was toast. With the new starter, it fires up faster than ever! So, tip: if you turn the key and there is a 1-2 second pause before the starter turns, look at replacing it before you're stranded.
But there is a related, new problem now. When the starter died, I was temporarily parked in the middle of a road at a park, where I was meeting buddies to go camping. I needed to push the truck into a parking spot to leave it for the weekend so I could hop in with the others. It took a 3 point turn and a lot of wrenching on the stiff steering wheel to get into the spot. I noticed that power steering fluid had leaked out during this process. I learned later that it is normal for Fords to eject fluid when you turn the wheels with the motor off. (The cap on the reservior had been displaced).
Problem is, the pressure that blew the cap off the reservoir must have blew something else too, since after topping up with PS fluid, it kept leaking! Reservoir was drained within 2 HOURS of topping it up. I looked underneath and saw the big puddle but could not tell exactly where it was coming from. At a glance, it looked like it was leaking from a lower spot (i.e. gear box, as opposed to pump or reservoir). Can't rule out anything yet though. Anyone have an idea what was likely to have let go after my parking lot maneuvering with the motor off? Blew a seal..gearbox or pump? Why though, would something else blow if the fluid escaped out the cap like it's supposed to...?
Going to try Lucas for now but the leak is so large I am skeptical. Hard to justify a major steering box repair given the truck's age right now, even though the motor runs great. So many things this summer... synchronizer, starter, exhaust leaks, EGR valve, it's getting to be a big problem. And while I can do an oil change, t-stat etc I can't handle these big jobs so it's $$$$$.