Do you have a picture of one, hopefully #7? up
Autolite # 3924 should be a 3/4 reach plug with a 5/8 socket size, not correct for stock iron heads scope
I am breaking a pump gas iron headed motor now for a local customer, I put a set of Champion RJ86Y in it shruggy
I was hoping to find some Champion RJ12YC or maybe even some RJ14YC or RJ10YC but no hope in my current stock whiney

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)