As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE REPLACING AN ALTERNATOR, NOTICED THAT DRIVE GER RETAINING NUT WOULD NOT RUN DOWN SUFFICIENTLY TO INSTALL SAFETY. DISCOVERED 2 DIFFERENT SPACER SIZES ON OLD AND NEW AACT. REMOVED CORRECT SIZE SPACER FROM ANOTHER OHC ALTERNATOR AND INSTALLED. CONTACTED FACILITY TO INFORM AND ACQUIRE CORRECT REPLACEMENT SPACER.