That's some good detective work there, horgantrevor. Thanks!

I'm fairly certain it's the water pump now. I found a leak on the top of the water pump where it attaches to housing for the thermostat. A bolt's head broke off letting it leak when it gets really hot. I'm thinking when it overheated, it showered the rest of the water pump with super hot coolant and washed out the bearing.

I replaced that damn water pump in 2003. Damnit.