Do the DS. No need for the spacer, if you do both you may have problems later. I did the spacer first when I was at 2.5" then I went with the MC 3.5" and changed out the DS, also added EVO skid plate. Well that spacer wound up pushing the exhaust onto the skid plate which eventually started to rattle. Brought it to a shop an they cut 1/4" out of the spacer and its fine now.

 

x2, on the drive shaft. Aside from fitment problems from aftermarket skids, I ran into problems when I installed my Dynomax Evo exhaust. The spacers pushed the y pipe too far back that the bend was touching the chassis which would cause rattling. I recently took off the spacer and will be looking to get an aftermarket DS....

 

Driveshaft. Dealer told me to do it now, or the stock will wear out prematurely with 4" of lift. Plus it's a double cargan style.

Sent from my iPhone using JK-Forum

 

I have the spacers on my 12 jku with 3.5RK lift and my driveshaft still rests on the exhaust with suspension droop. My down travel is actually limited by the shaft and exhaust. The driveshaft probably won't last much longer at the angle it's at always then I will get double Cardin shaft