Found the photo, but its states Mk 3 (left) and REC (right). So I may be wrong about the different switches, but I think I did have problems swapping the switches between my Mk2s and Mk3s. Sorry, not much help
http://i24.photobucket.com/albums/c34/PRS-Ian/MesaFootswitchCSIIIleftRECright.jpg
Ian