Where is the drain plug on a 1997 cadillac de ville radiator?

The 1997 Cadillac DeVille doesn't have a drain plug on the radiator itself. Radiator fluid is drained from the engine block's drain petcock (a valve) instead. You'll find this petcock on the lower portion of the engine block, usually near the thermostat housing. Consult your owner's manual or a repair manual specific to your 1997 Cadillac DeVille for the exact location.