The earlier ones did, I think by 75-76 all the 440s came with the 5/8 peanut plugs till the end of production.
that would be news to me... I've had several sets of late 70's 452 car heads and never saw this before. I have a 78 440 sitting between the fenders of a 67 NYer in my yard right now, I'll go down and look but I've had that engine in the car for 7 years and it takes the same big 13/16 Champion 12's spark plugs as every other big block I've dealt with. I also had a 77 400 in my truck for about 50k miles, changed the plugs in it more than ones during that time. Both of those engines came from C body cars and I have every reason to believe they were in factory condition when I got them. I have several other 76-78 400's and 440's down in the parts pile, maybe I should do an audit and look for this weirdness.....
