My 1984 Ford has been loosing antifreeze. It has a 5.8 liter engine. There are no external leaks that I can see, but I do see some white smoke from the tailpipe. By the sounds of it your white smoke is caused by antifreeze.
White smoke is produced when coolant is burned in the engine's cylinders.
A cracked cylinder head is the most likely cause of your problem. Coolant is forced through the crack into a cylinder by the cooling system pressure. Replacing the cracked head is the only recommended repair. Before installing a new head, there are a couple other ways coolant can enter the cylinders. A leaking intake manifold gasket could allow coolant into the intake passages.