Radiator leaking

Sitting just allows corrosion and rust to set in. Did it have nice fresh coolant or dirty old water. Going to be a good idea to change out the thermostat, hoses, fan belt, The diff did not keep it from cranking up and running, why have you not been cranking it up, Its wise to do so, I would suspect the trans filter, fuel filter to be gummed up & the fuel tank too, and the gaskets too. Vacuum lines dry rotting. Mice to be eating the air filter & wires and so forth. Brake lines corroding on the inside of lines, event the rubber lines down to the calipers. The worst thing is to let them just sit around and in the blistering sun and cold. Its just normal decay.

Thanks for the answer. The coolant was changed a about two years ago when I had to replace the heater core. I also changed a couple of houses but not all. I do run it once in a while to burn off the gas but it has been a few weeks. I only use the truck to haul dirt bikes, tow a boat and occasionally for work. It is a 2002 with only 140,000 miles. I am getting the diff rebuilt this week. I guess I will change the hoses and thermostat. Thanks again for the explanation.

That lower hose is high dollar. I did mine & top hose about 10 months ago, when I did my water pump, thermostat & belt. After seeing how high that lower hose was I went ahead and paid the extra money for the Motorcraft thermostat too. Mine set for most of 8 months as I was in the Hospital and I had to rebuild my rear brakes & a full tune up, Intake gaskets, Battery & terminals, The vacuum 90 degree hose fittings under upper intake cracked open ($13 each), Remove & Clean my throttle body & IAC & MAF & new air filter as rats made a nest in there, and 2 oil changes and all filters. Its runs great now. And it was running great before it set too, but sitting does it. My brake pads froze to my disc and peeled off. I saved my old cooling hoses as they were not real bad but replaced them as I had to take them off when I first started the truck and drove it I saw wet stuff in my front fender well and saw it was from the water pump, then After changing the oil a few days later I checked the level again and saw it was full of antifreeze, so I fixed that and changed my oil & filter a second time. That was just the truck my suv battery shorted out and burned up the wires an fried my, computer, fuel pump and lights ect. I am still working on it but it is back up and running, but now my trans leaks and its idles at 2000rpm I think because the intake gasket is leaking too. As I had to rebuild the throttle body which did nothing to fix the idle and doing it I saw the center section of engine is all wet in back. I had 11 surgeries and I am back up and running. I did not mean to sound rough on you in my post above I just know it does not take long before they can go to waste and cost alot to be road ready again, I was too into what I was going threw to even worry about mine.