1972 Ski-Doo Shop Manual, Page 73Get this manual
CHAIN CASE 1-12-03
NOTE: On Elan models, remove nut securing hinge rod to reinforcing cross support8From the inner side of frame, remove the nut securing chain case lower bracket and remove the bracket9Remove nuts, washers and "U" clamp holding the chain case to the frameRemove the chain case shim(s) if installedUnhook brake lever springMove chain case towards drive pulley to disengage special screw (hinge rod)10On Elan models, remove the drive axle11Using two (2) large screwdrivers inserted between chain case and frame, pry the complete assembly from vehicle (fig1-12-5)