With CFM, in many cases, you won't have any choice but to buu their parts..if available. And to my knowledge, only outside the US and on newer machines will you find an actual rear diff with a locker or as we like to call it here in the US. "Turf Mode". It is at or near impossible to have one shipped to the US as well. So I don't know what you have found here, but if it is possible to install and has the exact same gear ratio as the front, there would be a lot of interest. In any case our information center has a list of all the known CFM parts houses. What year is this CForce 600?