70 sierra Grande overheating

[towbar]

if its a head gasket\cracked head, you'll have the tail tail steam out the exhaust that never stops......at least until you run out of coolant. Also you'll have the sweet smell of coolant out back if your running anti-freeze. You should be able to do a compression check or a leak down test to determine if its a head issue. Heater core signs could be coolant in the PS floor board, smell of anti freeze inside, heavy windshield steam/fog with the defroster on.