Park the truck on a level surface and let the engine cool completely
Set the heater controls to full hot
Open the hood and remove the radiator cap only when the engine is cold
Place a large drain pan under the radiator drain area
Locate the radiator petcock at the bottom of the radiator
Open the petcock slowly and drain the coolant into the pan
If equipped, remove the engine block drain plugs to drain more coolant
Open the coolant reservoir cap to help the system drain
Disconnect the lower radiator hose if more complete draining is needed
Allow all coolant to drain fully from the radiator, hoses, and engine
Close the petcock or reinstall the drain plugs after draining
Reconnect any hoses removed
Dispose of used coolant properly at a recycling or service facility