I have a 2001 Tundra V8 4.7 access cab. It has about 108K on it (I bought it a few days ago) and I do not think that the spark plugs have never been replaced. I understand that the OEM NGK Irridium are the best. The only thing I do not know is how to replace them. Is that difficult? I am a handy man and good with tools. How can I replace them?