1966 dart front brakes?

I dont know what you ordered, But your 66 Dart with slant 6, if original has the small 9 inch drums, and 13 inch wheels. Lots of guys swap them out to front disc brakes. You can swap them to the Kelsey-Hayes, 4 inch wheel bolt pattern, or to the 73 up 4.5 inch bolt pattern. Your 13 inch wheels will not fit the 4.5 bolt circle, Im not sure about the Kelsey-Hayes set up.
Another swap you could change to, is 10 inch front drums, with 4 inch bolt pattern.
What ever you choose you will have to change the spindle, and bearings for that brake style. For the 4.5 type you will have to change the upper control arms also. Thier is more but i cant think of it all.
Do a search in this forum, thier are lots of threads about swaping out front brakes.

I hope I havnt confused you Its not that hard.

Dave