And guys thank you OH SO MUCH its an EXPANSION TANK!
I'm not sure if this was a smart a$$ comment at me to be mean or if it was just a poke, but there is a reason I asked. I am not sure which it was on that older truck. Newer cars use expansion tanks almost always, while many older cars used overflow tanks. There is a BIG difference and a BIG difference in the total cooling system operation, and I asked to help clarify(because many people usually don't know the difference and mix up the names) so that I can help diagnose it.
But if it was a mean remark, by all means diagnose it yourself