Okay, here's my latest nonsense: I'm losing coolant and I can't tell why:
1. When I brought the truck home, it had an obvious "big drip" from the lower rad hose under pressure. This stopped after replacing the clamp. Also gave me the opportunity to flush the coolant. I was hoping this was the problem, but I still lost an entire overflow reservoir after my inaugural beach drive.
2. No (obvious) coolant in oil, or exhaust. Passed a cooling system combustion gas test just now, which makes sense since the OHV shouldn't usually blow head gaskets without catastrophic failure, right?
3. No other obvious leaks. Planning to replace thermostat+housing anyway, but I feel like that's the common leak on the SOHC, not the old 4.0. Google refuses to exclude SOHC search results no matter what I try.
I'm suspicious of maybe a heater core leak going unnoticed getting mixed in with evaporator condensation? But no smoke or coolant smell in the cab.