I just bought a 2002 Chevy Suburban with 94,000 miles. It looks like the previous owner neved changed the spark plugs so I figure it's a good time to do so. The current spark plugs are AC and the type corresponds with the number in the owner's manual. Naturally, the local parts houses do not have spark plugs with the same part number. I've also gotten conflicting information about the gap. Some sources say .040 while others say .060. What is the best spark plug to use? AC iridium? One of the Bosch spark plugs?