How do you replace the spark plugs in a 2004 GMC Yukon?

To replace the spark plugs in a 2004 GMC Yukon, first, disconnect the negative battery cable for safety. Remove the engine cover if applicable, then carefully disconnect the ignition coil connectors and remove the coils. Use a spark plug socket to unscrew the old spark plugs, then install the new ones, ensuring they are properly gapped. Finally, reconnect the ignition coils and battery cable, and start the engine to check for proper operation.