Ray wrote: > Hi guys, for those of you who've done it, what did u use > to convert the 18mm rear sensor opening to accept the > earlier 12mm senor Go to your autoparts store and look in the help section. There is a sparkplug adapter part. It's 18mm you will have to tap the inside of it to 12x1.25 and cut the top part off to get the older type O2 to screw in. RK