Has anyone been able to find the exact replacement for the "factory plugs" (AC # 41-921)? I replaced the factory ones around 100K miles even though they were still working fine. (Yeah, I broke that old rule: "If it ain't broke, don't fix it")

The owner'* guide says to use that plug for a replacement, but no one had 'em. I couldn't even buy them at the dealership.

The computer database at the dealership and several auto parts stores said to use an AC #41-101 plug. The 41-101'* I put in at 100K miles didn't even last 50K miles and I wonder if the difference is in the design. (The 41-921'* have two opposing pointed firing tips, one on each electrode, while the 101'* only have one)

Later, Joe

most run the NGK TR55'*. You may or may not know that NGK actually makes the plugs for AC Delco.

Yep, I saw the NGK logo stamped right on the AC plug.
I paid almost 7 bucks each for AC'*. Is the NGK version cheaper and is it 2-tip design?

Probably not much cheaper. A good Iridium is the replacement. Avoid Bosch on the plugs as they get eated quickly in our waste spark setup.