67 vertman is right. hot hemi heads have a few list you can get information from. first two numbers indicate the year. The only thing I have never found is the list that tells you what vehicle it came out of specifically. Maybe 67 vertman will tell us his secrect for that!! Go to Facebook and search groups. there is one called old Hemi's and another you need to get with called first gen hemis and also first second hemis.