Positive acting differentials of the type having toothed drivers and couplers which automatically connect the two axles together to provide optimum traction for the vehicle, yet releases one axle when the vehicle is proceeding around a curve without drive wheel slippage, whereby only a single axle is engaged through the drive system. In assemblies of the type wherein the axles are retained in the assembly by a C clip, at least one driver is slotted so as to provide space for the insertion of C clip during assembly. This allows selection of the driver and coupler thicknesses without being restricted by the possible positions of the C clip groove in the axles during assembly, and reduces wear in the driver and coupler teeth by eliminating asymmetry between the engaging drivers and couplers. Preferred and some alternate embodiments are disclosed.