EVIDENCE OF LOWER AFT FUSELAGE DAMAGE IS FOUND ON A THROUGH FLT INSPECTION WITH NO EVIDENCE OF GND CONTACT BY THE TAIL STRIKE PLATE ON A B737-400.

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WE TURNED FINAL AND WERE CLRED ILS RWY 8L CYVR. THE CEILING WAS APPROX 3700 FT BROKEN. WE BROKE OUT EARLY IN THE APCH AND CONTINUED VISUALLY TO THE RWY. THE CAPT CALLED FOR FLAPS WITHIN ACFT LIMITATIONS. DURING THE APCH; THE ACFT MAINTAINED LOC AND AT ONE POINT WAS SLIGHTLY ABOVE THE GS UNTIL IT WAS SLOWED DOWN. THE APCH SPD ON FINAL WAS +/-5 KTS; AND THE CAPT SEEMED AWARE AND WAS CORRECTING FOR AIRSPD DEVS. WE CROSSED THE THRESHOLD ON SPD ON LOC ON GLIDE PATH WITH ENGS SPOOLED. FOR A BRIEF SECOND AFTER XING THE RWY THRESHOLD; THE ACFT LEVELED OFF AND THEN CONTINUED TOWARDS THE RWY. I DO NOT RECALL THE EXACT HT THE PWR WAS REMOVED; BUT IT FELT A LITTLE HIGHER THAN USUAL. THE ACFT WAS FLARED AND THE PITCH ATTITUDE WAS APPROX 9 DEGS AT TOUCHDOWN. THE LNDG WAS VERY SMOOTH AND THE SPD BREAK AND THRUST REVERSERS DEPLOYED NORMALLY DURING TOUCHDOWN AND ROLLOUT. WE TAXIED IN; COMPLETED THE APPROPRIATE CHKLISTS; AND BID THE PAX FAREWELL. MANY OF THE PAX COMMENTED ON THE SMOOTH FLT AND LNDG. NONE OF THE FLT ATTENDANTS OR PAX COMMENTED ON HEARING OR FEELING ANYTHING DURING THE LNDG. AT APPROX XA30 I WENT TO DO MY PREFLT WALKAROUND. WHEN I GOT TOWARDS THE AFT FUSELAGE; MY WALKAROUND PATH WAS FORCED UNDER THE ACFT DUE TO THE POSITIONING OF GND EQUIP. I DID NOT WANT TO WALK OUT IN THE MIDDLE OF THE ACTIVE RAMP TO GET AROUND SOME VEHICLES. AT THAT TIME I NOTICED SCRATCH MARKS ON THE UNDER SIDE OF THE ACFT APPROX 13 FT FROM THE TAIL STRIKE PLATE. I IMMEDIATELY WENT TO CHK THE TAIL STRIKE PLATE AND SAW NO INDICATIONS OF CONTACT. I COMPLETED THE REMAINDER OF MY WALKAROUND AND BROUGHT THE MARKS TO THE CAPT'S ATTN. HE THEN WENT OUT TO LOOK AT THE MARKS. WE BRIEFLY DISCUSSED THE MATTER AND DECIDED TO CALL MAINT. THE FLT WAS THEN CANCELED. BOTH THE CAPT AND I WERE UNSURE IF WE HAD CAUSED THE DAMAGE OR IF IT CAME FROM A PREVIOUS FLT. WE HAD NO INDICATIONS THAT THE ACFT HAD CONTACTED THE RWY.