O'Reilly Auto Parts in Fayetteville, TN had them. I don't think it's unusual for those numbers to be in stock around this area, at least. The ones I have trouble finding are the "C" prefix commercial plugs, such as a CR45, etc. They have a much larger center electrode, and were designed for delivery trucks, taxicabs, etc., where lots of stop & go driving was done. Commercial plugs would outlast regular ones about 3 to 1 in the dirt track race car.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!