1988 F-250 460 coolant leak

Look for a leak around hoses and water pump, check the oil to make sure it is not going into the oil, that would be a head gasket, also any white sweet smoke coming out the exhaust?

Heater core and radiator. You smell anti-freeze in the cab if it were a heater core, windows fog up.

I think I can rule out the heater core...windows do not fog. I plan on letting the truck run with cardboard underneath to see if I can gain any intel on where to look i'll check the exhaust smoke for the 'sweet' smell...if this is true...would it have to be a head gasket?

i checked the oil last time i ran the truck and it did not appear to have any water present. would that rule out a head gasket?

Not yet, the coolant is going somewhere. Do you get heat out of the heater core into the cab?

yes...the heat in the truck works fine

Have you looked anymore for leaks, cardboard under truck, exhaust smell? How often do you add coolant? How fast does it go down?