What type of dart do I have?

Your Holley car is not stock, neither is your distributor and radiator. Your windshield washer system is totally missing. You also have a couple of "boxes" on the inner fender that aren't stock either. I looks like you have the spark plug heat shields on the opposite side they should be. When you say you have a "Hurst Trigger Shifter", does it actually say Hurst on it? The stock shifter in '66 is a Inland shifter, which does have a trigger to get the shifter in reverse. An 8 3/4 rear could be stock along with the Kelsey Hayes disc brakes. Buckets seats in a GT is common.