The steering box is specific to the square bodies. There are minute differences 1973-76, 77-79, and 80-86. The diameter of the input shafts vary over the years .73", .787", .80", and imperial vs metric hose ports, etc. It is advertised on ebay as part number 27-7522. Here is a link to one:
https://www.ebay.com/itm/394978344976