What is the difference between the AC Delco R44TS and the CR44TS? I know that the "C" stands for commercial (double checked on the Delco website so don't try to tell me that the C stands for copper because it doesn't), but what does that mean in the real world? Better plug but more expensive? Better for low RPM/high load operation like a tow truck or taxicab? Thanks, -Bob Cunningham
Some years ago, I compared a regular plug to a commercial plug, and the only difference discernable was the thickness of the metal going from the ground to the center electrode. It appeared to be much thicker, so I am sure it would hold it's clearance better. This may not be the only thing, but it is part of the change.