Determining /6 year

[RustyDusty]

How do I determine the year of my Slant 6? It was added later in my dusters life. I've read up on this site, but have been unable to find the date area it is talking about: http://www.yearone.com/updatedsinglepages/id_info/mopar/mopar casting numbers/castingnumbers.html

The casting number is 2806830 which means it's between 1968 – 75

 

[nuttyprof]

See http://www.slantsix.org/articles/parts-matrix/jpg.htm, also there are some numbers on the top of the block below #1 spark plug that give the year etc.