Right. Carquests' "good" line is Standard Ignition. Their crappy line is Wells. In the Standard Ignition category, you generally find a part number like CH410. Then for some applications, they will also have a CH410X, and the 'X' signifies that for this particular part, even Standard has a version of it that is cream de la cream. An 'X' suffix on an ignition part at Carquest means the best within the Standard Ignition line for that particular part. Davey

PS... at Carquest not ALL Standard Ignition parts have an 'X' variant. When I worked there I noticed it mostly on stuff like this distributor cap...items that saw relatively tough service and for which you could get a cheap one, but for which better quality translated into a measureable increase in performance or function. Many point sets had an 'X' variant, as did many dizzy caps and condensors. Ignition control modules and pickups also did very often. Just thought you'd like to know. Davey