Abstract: A propeller shaft nut lock assembly for retention of a propeller shaft bearing assembly includes an externally threaded shaft surface threadably receiving a thrust nut that includes an outboard undercut groove therein to receive a cup lock that is shifted to locate an eccentric segment on the cup lock into interlocking engagement with the undercut groove when a thrust nut lock centers the cup lock on the assembly, and wherein the cup lock includes a plurality of axially extending bendable tangs to indicate that the thrust nut lock assembly is seated in load transfer relationship with the bearing assembly.