ACR CAPT DISCOVERS DURING TAXI AT DTW THAT HIS RELEASE INDICATES THE ENGS FOR THE ACFT ARE NOT OF THE TYPE ACTUALLY BEING USED.

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FOUND ALL ACFT SYS NORMAL DURING THE CAPT PREFLT CHK. RAM AIR TEMP/EPR GAUGE; ENG PLACARDS AND SPD CARDS ALL COMPARED FOR CORRECTNESS. DURING THE 'TAXI CHK' WHILE TAXING OUT; I NOTICED THE FLT RELEASE SHOWED THE ACFT TO BE CONFIGURED WITH 'JT8D-9' ENGS. HOWEVER; THE EARLIER CHK (MENTIONED ABOVE) INDICATED 'JT8D-7' ENGS. WITH GND CTL AUTH; I PULLED OUT OF THE TAXI SEQUENCE TO THE RUN-UP PAD TO INVESTIGATE FURTHER. I CONTACTED DISPATCH; WHO CONTACTED MAINT CTL. MAINT CTL ADVISED THAT I RETURNED TO THE GATE. FURTHER INVESTIGATION RECONFIRMED AN ENG CHANGE AS NOTED EARLIER IN THE ACFT LOGBOOK. THIS WAS ACCOMPLISHED THE DAY BEFORE. EVIDENTLY THE ACFT HAD BEEN REMOVED FROM AN 'ENG INTERMIX' STATUS FOLLOWING THE ENG CHANGE; AS THERE WERE NO NOTES IN THE REMARKS SECTION OF THE RELEASE TO STATE OTHERWISE. AFTER FIGURING OUT THE PROB; A SECOND RELEASE; WITH APPROPRIATE CORRECTIONS; WAS ISSUED AND FLT WAS COMPLETED WITHOUT FURTHER INCIDENT. CONDITIONS THAT ATTRIBUTED TO THIS OVERSIGHT ON MY PART; I BELIEVE; ARE MULTIPLE ACFT CHANGES DURING A DAY OF FLT DAY; DARK CONDITIONS -- LIGHT INK (RELEASE PRINTING); SIMILARITY OF DIGITS; SUBTLE LOGBOOK ENTRY -- STATED ENG CHANGE -- BUT I DID NOT READ WHICH TYPE ENG WAS REMOVED/INSTALLED. IT WAS NOTED IN THE 'LOG ITEM DEFERRAL SUMMARY' 1/2 WAY UP THE PAGE IN THE MIDDLE OF NUMEROUS OTHER ENTRIES. PROBABLY HAD IT BEEN THE FIRST FLT OF THE DAY RATHER THAN THE LAST (FATIGUE FACTOR); I MAY HAVE CAUGHT THE ERROR SOONER. LESSON: AS THE DAY PROGRESSES AND NIGHTFALL OCCURS; IT IS PARAMOUNT TO PAY ATTN TO DETAILS.