B737 FLT CREW HAS NO 'DOWN AND LOCKED' INDICATION FOR THEIR NOSE LNDG GEAR ON APCH TO SDF.

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ON APCH TO SDF RWY 17L; AFTER INITIAL DIRTY UP AND STARTING THE LNDG CHKLIST; IT WAS NOTED THAT WE HAD NO LIGHTS INDICATING IF THE NOSE GEAR WAS DOWN AND LOCKED (GREEN LIGHT) OR IF IT WERE UNSAFE (RED LIGHT; LIGHT IN THE HANDLE; GEAR WARNING HORN). WE ELECTED TO LEAVE THE GEAR DOWN; BUT INITIATE A GAR TO DIAGNOSE THE PROB. I PULLED OUT THE QRH AND WENT TO THE 'UNSAFE GEAR INDICATION/MANUAL GEAR EXTENSION CHKLIST;' BUT DECIDED THAT THIS WAS NOT APPROPRIATE TO THE SIT; BECAUSE WE DID NOT HAVE ANY 'UNSAFE' INDICATION. NO OTHER CHKLIST SEEMED TO APPLY. WITH THE FO FLYING THE ACFT ON DOWNWIND; I WENT TO THE NOSE GEAR VISUAL PORTAL AND VERIFIED TO MY SATISFACTION THAT THE NOSE GEAR WAS DOWN AND LOCKED. WHEN I RETURNED TO MY SEAT; I TOOK CTL OF THE ACFT AND HAD THE FO GO TO THE VIEW PORTAL TO VERIFY MY FINDINGS; WHICH HE DID. WE TURNED IN AND SHOT AN UNEVENTFUL APCH AND LNDG TO RWY 17R AS PER APCH. WE NEVER DECLARED AN EMER ; BUT DID ASK ON TWR FREQ IF SOMEONE FROM THE EMER VEHICLES COULD PIN THE FRONT GEAR AFTER WE LANDED. AFTER WE BROKE OUT; BUT BEFORE LNDG; TWR NOTIFIED US THAT OUR NOSE GEAR APPEARED TO BE DOWN AND LOCKED. WE LANDED; CLRED THE RWY; AND WITH THE EMER VEHICLES PRESENT; I TOSSED OUT 1 OF OUR GEAR PINS FOR THE NOSE TO BE PINNED; WHICH WAS DONE. WE THEN PROCEEDED UNEVENTFULLY TO THE GATE. SUPPLEMENTAL INFO FROM ACN 539985: CHKLIST MIGHT BE IMPROVED IF TITLE WERE CHANGED FROM 'UNSAFE GEAR/MANUAL EXTENSION' TO 'NO DOWN INDICATION/UNSAFE GEAR/MANUAL EXTENSION.'