Abstract: Spline members are retained together by a split retaining ring which is urged by a ramp on one of the members from an installation position into an assembly-disassembly position in an annular groove on the other member and on proper mating of the members assumes a retention position in this groove and in another groove on the one member which is ramped on one side to provide for disassembly by reversal of the assembly operation. To facilitate the assembly operation, the retaining ring is formed with its two end portions radially displaced over substantial distances from the normal circular shape so that the ring is supported along its entire length when in the installation position by the groove in the aforementioned other member.