Will a 66 drivetrain swap in to my 68??

If you're going with the 4 speed that's in the 66, and your car is an automatic, you will need the pedals from a 67 and up A body! The brake lines on the 66 will work, but everything would have to be swapped over! That Dart has tons of good parts on it, waaaay better than a parts car IMO!!