they should mount up the same for all the arms. as i have a 2012 xtx skid and an 2011 apex xtx skid, i can tell you there is a difference in the wheel mounting location and the lower spring where it hits the rail between the 2 skids. the 1st outer wheel is further ahead on the 12 and separate from the spring mount. on my 11, the wheel and spring mount are combined.