I really need help
 

this is my story, a year ago I bought a Buick GS 455 engine and the day I first bought it it was running, but after driving home, the shift linkage in the steering column broke now for the past year. I’ve been getting steering columns that don’t fit and I just got the right steering column. After trying to put the steering column into the vehicle, I noticed that the steering column ends in a 1 inch double D. My steering shaft ends in a female 3/4 of an inch spline. If you know any part that would help me in connecting the steering column to the shaft it would be very helpful the only way to get the vehicle in my name, and to get the safety, updated in my state, is to get the car running and take it to a mechanic. I just really need help and I’m really trying not to lose my car. Please help me. Thank you.

Most steering column shafts are the same. Could you have the wrong part?
Also, I believe what you are calling a double D is the universal joint on the end of the shaft.There is usually a pinch bolt that holds the upper portion of the u-joint on the shaft
You don't provide the year so we are at a loss here.. Can you maybe post a pix so we could get a better idea of what you are trying to say.

The car is a 1972 Buick GS 455. Sorry for all the confusion. At the current moment, the army base I live and work on towed the car so I can’t provide a picture but I will as soon as I’m able to