RE: replacing antifreeze in 02 ram 4.7L, what to use
I second "NYPANAMA42" recommendation. Flushing a system as big as you find on the Ram is likely to require you to buy gallons and gallons of distilled water. So the tendency is to use tap water. That's almost worse than leaving the factory fill alone. Your simplest solution is to do the typical drain and fill using the Mopar coolant with distilled water. Unless you have some kind of sludging or contamination, that's all you really need. Don't use tap water unless there's no other alternative.
If you just can't do the Mopar route, then drain the block and radiator. Fill with distilled water. Drive for 5 mi. Drain, refill with distilled water. Drive 5mi. Drain and then add enough pure antifreeze to equal 50% of the capacity--eg, 18 qts, fill with 9 of coolant. Then top of with the distilled water. That way the pure water remaining in the system won't over dilute your fill.