68 dart gt convertable wont go up?

If it's like an early A, you'll need to pull the back seat to access the pump. It's held in this recess on the seat back support bracing with 4 rubber grommets, Pop it out of there - on the tank you'll find the fill plug. On the early A they specified Dextron - check your owner's manual for whatever it calls for. Add some fluid then raise and lower the top, filling as needed the pump reservoir. Try not to overfill as the fluid has no place to go. Hope this helps!