OK. Look at your front driveshaft where it comes out of the transfer case. See the rubber boot? It is at an extreme angle at stock. The issue, as I understand it, is when you lift it on a 2012, at any height, the angle is even more extreme. At some point, the angle becomes such, even if you dont flex it, that that boot will become so pinched, it will tear itself up. IFIRC, even at 2.5 inches of lift, it will be enough to pinch and rip the boot. Some swear it hasnt happened to them, but the key word is "YET"

I have a 2012 rubi 2 door, and i will be going with a 2.5 inch RK lift. It ends up reallly lifting about 3 to 3.5". If you flex at all, it can end up pinching the boot to the extent it will rip eventually. To ensure I wont have any issues, I will be buying a 1310 Coast or Tom Woods DS. Since I have a 2 door, I will also be replacing my rear DS. YMMV as to whether you can get away with not doing either, but I have built up Jeeps before, and for me, I dont want to take a chance, and will be building my rig with new DS's, front and rear.

Kinda a bummer when your out on your first wheeling trip, and you rip the boot, and have to do a new driveshaft after your first wheeling trip. I like to wheel, and come back with the idea that I didnt screw anything up, and can go right back out again the next week, and hit the trail again with no repairs.

I purchased a new Land Rover D90 when they first came out in 1994, and after every trip, I had something to repair or fix. That got tiresome after a while. I know I can build a Jeep up right the first time, in such a way, that I can go out every weekend, wheel hard, and do it over and over, without having to worry about this ever again.

Again, YMMV. Good luck with your build. Some of us tend to error on the side of caution, and overbuild their rigs. Im one of those guys.

Best,

D