Thanks for all the responses, I think I got every one sideways and I am sorry. Since I don't yet have a Revo of any kind, I was thinking it (meaning the differential) only hit the diff housing and as several of you all point out the RCM page does specifically say that the "chassis" needs to be modified.

So the answer that their is a plastic piece that needs to be dremmelled a bit on the E-Revo's chassis makes sense to me now.

Thought I have to agree, I would like to see pics on that myself, especially since to get this set up it is another 200 dollars and change just for the diffs.

Thanks again for the help.