With the SYE, you will need a new driveshaft. With the new driveshaft, it will require you to use adjustable rear upper control arms to set the pinion. This also requires you to use an adjustable rear track bar or an angled rear track bar bracket to use your stock track bar (JKS makes a good one). I would get adjustable arms first if you have to pick one. Look into Savvy double adjustable rear uppers. If not those, Rock Krawler is cheaper and works. It's best to do it all at once though
Have you checked your u-joints?