C6MDW

Hi sorry if this is in the wrong section, but I am looking at gearbox options. can I fit a 6 or 8 speed gearbox in a car that was a manual what inputs are required and can they be programmed out or amended. I read something about the speed sensor pickup was through the abs computer but could be swapped to the shaft sensor ? any help or pointing me in the right direction would be appreciated kind regards mark