Add Shoulder belts to 66 Dart Conv?

You guys should really think about where and how rear shoulder belts are installed. A poorly positioned belt could be a lot more dangerous than none at all.
The are used in the front to keep the occupants head from striking the A) Steering Wheel, B) Dash Board, C) Windshield and D) Exploding Air Bag....since none of those things exist in the back seat of any car, they really serve no purpose and in the event of a severe front impact can actually INCREASE the chance of neck damage by limiting the forward movement of the upper torso to just the head and neck, as oppose to a lap only belt which will spread the inertia load over the entire spine.
OP, strap your kids in the back seat, and lean them as far forward as you can...if their heads don't contact anything solid from that position, you're good just the way you are.