Quote Originally Posted by rspears View Post
The "Denso" makes sense as you explain it. I'm familiar with "heat range" on plugs, but didn't see any reference to 1973 in the question, so the numbers didn't really make sense to me. "Champ" and "AC" were no issue, but "Tapper" thrown in was enough to put me in a tailspin . Thanks, Mike.
well if you had a chevy it may 1973 was about the last year before they took the nuts off the 454 the 781 head s were a short reach taper plug
and about that time frame so thats a good place to look in the book and should be a rn8c or a rts 44