2001 Gmc Sierra Coolant Leak Originating Somewhere Front Cannot Tell Leaking

I have a coolant leak originating somewhere in the front , I cannot tell where it is leaking from, most of the coolant seems to be leaking from the left side as the left tire and brake are covered with coolant.. Truck is NOT overheating at all and I have been told it may be everything from freeze plugs, a hole in the radiator, to the heater core leaking... Otherwise the truck runs as good as ever. What would the likely source of the leak be? Any Suggestions?