From all I've gathered on the d-dart spec's and numbers, they were for race-only application purchases from dodge.

The cam and holley were installed in a 10.5:1 compression 273, with the single plane intake and dual point ignition. it was only a special option in '66.

There isnt anyone out there that I've found that has a Spec or can grind a D-Dart Cam. I contact a number of custom grinders, and a few of them even told me that if I found one in an old race car to let them know and they'd pay for me to send it to them so they could duplicate it.

I have yet to see a car with the d-dart package confirmed installed on the car. So if you are lucky enough to find one, snag it.