Originally Posted By lewtot184
those are the wrong plugs. they're 3/4" reach and iron heads use 3/8" reach. use an autolite 85.


Late 452 heads in motorhomes, and what are termed POLICE motors, used the peanut plugs because of the extra cooling passages that run around either side of the plug and into the block, they do not use the standard mopar 3/8 reach plug.

running up my post count some more .