So the cooling system saga continues. On Friday I drained the radiator, and made a solution of Cascade and TSP. About 1/2 cup of each in a gallon of hot water. Filled the rest of the way with straight water. Ran for about an hour, then drained. The shit coming out was basically black. The radiator is visibly cleaner. Much of the Dexcool sludge was removed. Surprisingly, to me anyway, more rust chunks came out, and the block drains were again plugged solid. I ran the truck for 5min or so with the hose, flushing until clear. Drained and filled with a slightly stronger mixture of the same solution. I’ll run my errands this week with the truck, then drain on the weekend. Hopefully by then, this thing starts coming out clean.