68 Charger steering issue

First determine where the extra play is. Have someone rock the steering wheel back and forth while you look at all the steering components. The coupler, box itself, pitman arm, idler arm, tie rod ends, etc, are all places that can be worn or out of adjustment.
There is definitely play where the steering shaft goes into the coupler. I removed the steering column and the coupler fell off the end. I'm guessing the rectangular parts were turned wrong. When I turned them the other other way. I would almost have to tap the coupler back on with a hammer.