The D55 should be the same assembly as the other D models in that you remove the spark advance lever, manual throttle lever, and disconnect the horn cable at the front lower end of the steering column. There is also a clamp that needs to be removed holding the control unit assembly to the steering box front end. Loosen the 4 bolts holding the steering box to the frame and remove the steering column clamp attached to the instrument panel to lower the steering column to allow clearance to slide out the control unit assembly toward the rear window. Remove the control unit assembly with horn cable and then the steering wheel nut will be exposed. Remove the nut and carefully pull the wheel from the keyed steering shaft.
The steering wheel detaches from the bottom of the steering column in the engine compartment. You have to remove the connections for the distributor advance and the throttle advance, There is a clamp that holds the whole thing in place that you will need to remove. Pull the whole unit up from the inside and you will see the screws that hold the steering in place. Good idea to pull it out as there are two rods and the electrical wire for the horn that passes through a 1" ??? steering shaft. I changed the wire and greased the rods, Good luck. Jim Cooke