Thanks for the help on these heads. I'm still trying to lock down more info, like when they were produced. Rick E. at Mopar Action once wrote that big block Mopar heads mid-1972 on up have hardened seats. Does that mean all 346 and beyond heads are this way? Sean ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html.