Shorty header install

How does the coupling and shaft come off the box. Does the steering column need to come all the way out?

There is a round pin you need to drive out of the coupling, don't loose the pin cuz you will need it when you reassemble; gravity has a funny way of taking control just as the pin comes out. You may be able to pull column back out of your way to gain clearance, try it and see what happens.