Hi All, I have a 1994 K2500 truck which has a coolant leak where one engine oil cooler line connects to the radiator. Driver's side, upper connection. These are the oil lines that often need replacing due to the rubber eventually giving way to a leak in winter months. There are two seals at this radiator connection. First, there is an o-ring (~1/2 inch diameter) to seal the oil line to the cooler. Second, there is a seal or gasket (~1.25 inch diameter) that somehow seals the coolant via a large thread/nut combo. I can see the nut, but not the gasket. This is the gasket/seal that is leaking coolant on my truck. Several GM parts guys have claimed that this gasket/seal is not servicable or available! Any ideas on getting this gasket? Is it internal or external to the radiator? I hope I don't need to buy an entire radiator. Thanks.