You will probably need to swap out the stock drive cups on the the UE diffs for some RCM style outputs, so that you can use the traxxas cvd drive cups- the UE ones tend to be a bit short/ shallow causing the cvd dogbone end to pop out. Mike sells the required items:
http://www.rc-monster.com/proddetail...d=RCMdiffshaft
or you can make your own from traxxas stub axle parts- just cut off the threaded portion:
http://www3.towerhobbies.com/cgi-bin...?&I=LXHFY7&P=7
And I have a tutorial (of sorts) of how to install them:
http://www.rc-monster.com/forum/showthread.php?t=8012