I have a high-mieage (290K) 2001 Sierrra with 5.3L engine.
At about 150K, it developed a coolant leak somewhere near the front of the engine, on the passenger side. At first, the leak was minor, but appears to be getting worse.
I replaced the surge tank/heater hose assembly when the leak was first discovered, with zero results. The inside of the water pump pulley is dry, so there is nothing coming from the pump weep hole. None of the leaked coolant is getting on the serpentine belt, and I can't see/feel any place where the leak might be coming from.