I had a 66 coronet with a slant. It moved just fine, would run 65 70 mph ok, was never a speed demon getting to those speeds but it did alright. Only saw one charger with a slant in it . This was a 68 with a 3 on the tree. I have a xharger brochure from 68. Havent looked at it lately i think it says V8 only offered on charger, but my 69 charger brochure says 6 or V8 we got you covered. Maybe my 68 charger brochure was printed late in 67. Rare or not id still pass on one and go for the V8. A car that slick just disappoints in the performance department with a slant 6 IMHO.
