The quick-connect fittings for the heater hoses tend to leak engine coolant. This problem commonly occurs because the metal housing has become brittle, which can break and cause leaks.Google+
Car Problem Reports
Chevrolet 1500 Pickup Quick-Connect Fittings For Heater Hoses May Leak Engine Coolant
Chevrolet 1500 Pickup Problem
Average Mileage: 143,500 mi (40,000 mi - 200,000 mi)
Visitor, 1993 Chevrolet 1500 Pickup, 200,000 mi
The pot metal "quick connect" receiver broke off at the treads into the intake manifold. Required removal of intake manifold to remove remaining threaded section and retap manifold for replacement.
Visitor, 1993 Chevrolet 1500 Pickup, 40,000 mi
Radiator failed three times !
Visitor, 1996 Chevrolet 1500 Pickup
This happened to my quick connect too.Fortunately there was no fluid loss but,when I started to remove the quick connect,it was so eaten up from the orange coolant that it twisted off inside the aluminum intake requiring extraction with special tools and re-tapping to clean the threads.