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dry block or refill on the radiator? Just get three gallons of 50/50 Prestone Premix and you'll be fine. Overflow takes less than 1, radiator right at 1 and the block holds the rest. Unless you have had the freeze plugs out, all you have is the overflow and the radiator to deal with for the most part.
BTW, the 5.9 will run exceptionally well and cool even very low on coolant... not that you would want to do that on purpose.