What was found
(CAN) DURING CRUISE PILOT REPORTED ENGINE OIL PRESSURE DROP AND QTY DROP, VIBS STARTED TO INCREASE AND THE FLIGHT CREW ELECTED TO SHUT DOWN THE ENGINE IN ACCORDANCE WITH QRH PROCEDURES. AIRCRAFT DIVERTED AND RETURNED TO GANDER. MAINTENANCE INSPECTED THE LP COULD NOT ROTATE BY HAND, MCD'S INSPECTED EXERNAL ONE LARGE FLAKE AND INTERNAL TO GEARBOX FULL OF PARICALES. SCAVENGE FILTER HAD LIGHT CONTAINATION AND NO EXTERNAL VISUAL OIL LEAKS WHERE NOTICED. SUSPECT TOWER SHAFT FROM IP TO GEARBOX FAILURE, ENGINE REPLACED AND AIRCRAFT RETURNED TO SERVICE. AWAITING SHOP FINDINGS.