A WRONG PART WAS INSTALLED IN AN ACR WDB.

Narrative

AFTER LNDG ROLLOUT; #3 THRUST REVERSER FAILED TO STOW. ACFT TAXIED TO GATE AND ENGS SHUT DOWN WITH #3 STILL IN REVERSE. APPROX 30 MINS LATER; #3 WAS RUN AND ATTEMPTS WERE MADE TO STOW THE REVERSER. THE REVERSER FINALLY STOWED AFTER RESETTING THE THRUST REVERSER AUTO DECELERATION CIRCUIT BREAKER. IT WAS DECIDED TO LOCK OUT AND DEFER THE REVERSER. I LOOKED IN THE MEL FOR THE PROPER METHOD AND NOTIFIED SYS MAINT CTL AND DISPATCH OF THE DEFERRAL. WHILE MAKING COMPUTER ENTRIES; I WAS TOLD THE LOCK HAD BEEN INSTALLED ON #3 REVERSER LEVER AND I FINISHED THE ENTRIES AND RELEASED THE ACFT. IT WAS CLOSE TO PUSHBACK TIME AS I DELIVERED THE LOGBOOK TO THE COCKPIT AND EXPLAINED THE DEFERRAL TO THE CREW. I ALSO LOOKED FOR THE LOCK TO BE INSTALLED ON #3 REVERSER AND OPERATED THE THROTTLE LEVERS FULL FORWARD AND AFT. I THEN EXITED AND PUSHED THE ACFT. UPON ARR; IT WAS NOTICED THE INCORRECT LOCK HAD BEEN INSTALLED AND THERE WAS CONCERN THAT FLT SAFETY HAD BEEN JEOPARDIZED. WHEN THE ACFT ARRIVED BACK AT SFO; I INSTALLED THE SAME LOCK ON #3 TO CHK OUT THE PROB. THE LOCK SEEMED TO FUNCTION OK; BUT THE CORRECT LOCK WOULD HAVE FIT BETTER. THIS WAS A GOOD REMINDER TO NOT ONLY CHK FOR A PART; BUT TO CHK FOR THE CORRECT PART.