hey stumpiey. Ive been looking at a shell for my mad monkey and the only thing that apparently comes close to fitting (not my experience, from another member i think) is the Proline Bulldog for the associated b4 with a section cut out the back. How ever (also not my own experience) The shell is too thin for the monkey chassis, but being the x2c with the narrower chassis than the monkey, there is a chance it may fit. Hope this helps.
http://www.apexmodels.com/gbu0-prodshow/PL3342-00.html its out of stock at apex in the link but im sure you can find it somewhere else.