Systems, methods and devices relating to lock assemblies for doors are disclosed. The lock assemblies include an end cap that couples a tail piece, cam or other latch operating mechanism to the plug of the lock assembly so that the latch operating mechanism rotates with rotation of the plug to operate a latch. The end cap includes a plug engaging portion that is configured to interfit with an end cap receiving portion of the plug to axially and rotatably fix the end cap to the plug.
