SYE stands for Slip Yoke Eliminator. As the name implies, its a kit that eliminates a slip yoke on a transfer case by converting the output shaft to a fixed output shaft instead of the splined slip yoke output.
the Rubicon NV241OR has a fixed flange output...there was never a slip yoke to eliminate.
You will still need a Double Cardan (also called a CV) driveshaft. The DC shaft will require adjustable upper control arms at a bare minimum, and lower control arms are recommended. You'll need to center the axle housing at full bump and set the pinion angle at ride height by shortening the lowers and extending the uppers.
Give this a read:
What is a CV shaft and why do I want one? - JeepForum.com