A B737-400 CTR TANK FUEL QUANTITY INDICATOR WAS DEFERRED AS INOP PER THE MEL. TECHNICIAN USED B737-200 SPECIAL PROCS FOR DEFERRAL.

Narrative

YESTERDAY CALLOUTS WERE COMING AT US LEFT AND RIGHT. I WAS CALLED OUT TO ACFT X FOR A CTR FUEL QUANTITY INDICATOR HAS ERROR CODE 1 AND 5. THE ACFT WAS FULLY BOARDED AND READY TO GO. I MEL'ED ACFT X FOR A CTR QUANTITY INDICATOR BEING INOP. WE WERE USING MEL AND WHILE PERFORMING THE MAINT PROCS TO DEACTIVATE THE FSU (FUEL SUMMATION UNIT); I ENDED UP USING THE PROCS FOR THE B-200 ACFT INSTEAD OF THE B-400 ACFT. WHICH THE B-400 ACFT CALLS OUT FOR PULLING AND COLLARING A CIRCUIT BREAKER AND THE B-200 ACFT CALLS OUT FOR CAPPING AND STOWING THE FSU CANNON PLUG FOR DEACTIVATION. I DID CONFIRM WITH MAINT CTL THAT I WAS ACCOMPLISHING SPECIAL PROCS MEL FOR MEL DEACTIVATING THE FSU AND COMPLETING A PLACARD. WHICH HE CONFIRMED! BUT WE NEVER VERBALLY CONFIRMED IF I WAS READING THE B-200 OR THE B-400 ACFT MEL. THIS IS WHERE I THINK WE LOST EACH OTHER AND THE MISTAKE WAS MADE. LASTLY WITH MAIN TANK MEL; WHICH I HAVE DONE MANY TIMES OVER THE CTR MEL; IT DOES CALL FOR CAPPING AND STOWING THE FSU CANNON PLUG ON 400 ACFT FOR DEACTIVATION; JUST LIKE THE B-200 ACFT ON MEL.