Is there ANY reason other than head gaskets that the upper rad hose would get hard after sitting? The hose is hard after it sits overnight but not all the time. No white smoke. No loss of power. No loss of coolant. No puddles of coolant or any sign of leaking. No coolant in my plastic bottle where i put the overflow hose into. Truck heats fine, same as it has always done. Hose has been like this for about a year that i can remember. No, I am not in denial i just want to be sure. My local shop owner and a friend who works on diesels say it's fine but i am a bit of a worrier. If they are done then fine, I will get it fixed but i want to make sure first.