I moved the original box back, the top rear hole became the front hole. The steering shaft inside the tube is 3/4” solid shaft which is the same size they use today. A double D is a ¾ shaft milled down, or you can pin a joint, damper or coupler it just depends on what you want to use for the column. You will need to lengthen the drag link. A word of caution here you want to keep the box centered. Last fall winter there was a few discussions on adjustable drag links to center the box and I have changed mine to an adjustable drag link.
