This is the OEM replacement for my 1998 GMC Jimmy (and all the GM Vortec V6's out there). The original plugs were still running smoothly after 152,000 miles but the gas milage was dropping. You can't beat that kind of dependability or quality so why even look for an aftermarket plug. They have changed the design and part number from 41-992 (my old ones) to 41-993. These newer plugs have a tiny spark wire extending off of the center electrode instead of the flat rod. I guess this functions like a "lightning rod" and makes the spark more "focused". NOTE: these are the Professional Platinum plugs; HOWEVER, the box is marked Iridium. Theses are not suposed to be Iridium plugs and are pre-gapped just like a platinum plug should be (around 0.06 on the 41-993). Maybe someone can add a comment if they know something. Yes its the correct box, both the boxes and the plugs indicate 41-993. Whats up with that ? Installing a spark-plug is not hard, in principle, (loosen, remove, insert, tighten) but plugs on the Jimmy (Blazer or Bravada) are not a simple job because of their locations. Once you learn all the tricks its actually not so bad (except #3 plug, even after you know what to do its 10 minutes by itself). Yes these plugs cost a bit more (at list price) than some of the others but these are the plugs you want in your GM engine to get the optimum performance and longevity (unless you plan on re-engineering the entire ignition system with after-market performance parts). Use a coupon code at Advance Auto and you can get 40% off! Or just spend a couple of bucks now and be done with it, you don't want to do this plug change often. Unless you plan on modifing the entire ignition system just stick with what was designed for your motor. If these plugs run as well as the originals, they will outlast my ownership of the Jimmy (or me). I have seen the mpg increase to the level I originally had when I bought the Jimmy (23.5 mpg highway). With the old plugs, it had slowly been dropping off over the last 30,000 down to about 20.7 mpg. I should have done this job 3 years ago.

My old AC Delco spark plugs showed some usage at 50,000 miles. Mechanic said they could have gone the full 100,000 miles. However, I felt a tune up at 50,000 with the AC Delco spark plugs with Iridium would only improve my gas mileage and provide a better performaning vehicle. Tune up at 50,000 may have been overkill, but the ride is a smooth one.