Know of a half dozen EBs running Klunes, including myself, with either c4 or manual and it works tits! Only adds 6 3/4" to the driveline and all I did was clock the 9" upward for a better u-joint angle. Amazing what the 4.1 underdrive does for crawling capability and you get four ranges vesus the factory high and low!!! Does require custom crossmember, but not a huge deal to build. Greg at Klune really ought to design and include a crossmember for EBs, but who am I to say. haha
The Atlas and Stak 4 speeds are really just a 2 speed with a planetary gear box, much like the Klune, added to the 2 speed TC.
Best $2,500 improvement I ever spent on my rig, but the Atlas and Stak have desirable plusses that many prefer over the Klune. Research and learn them and make your own call. Good luck.