I have a 52-3100 and the brake and clutch rods are on a rod that is mounted to the frame so the motor mounts would have nothing to do with them rubbing on the cab , I would think that the problem if the set up is the same as Mine frame to cab then it is the cab that needs to be fixed .You would have to shim it up or down or if it is rotted by the mounts You would have to repair the floor and mounts .
Pete
