Eight and three-quarter rear end driveshaft issue

Yeah, there is a special conversion joint that you need to use that has a shorter length for your driveshaft and a longer length for the rear end. I’ve used it two or three times, but I don’t remember the number for it. I’m not sure the auto parts stores can help you out either because they don’t seem too knowledgeable about such things. Maybe somebody here can chime in with the correct part number.