NEED TO CHECK/REPLACE OIL PUMP CAN IT BE DONE WITHOUT REMOVING ENGINE JUST NEED ACCESS TO OIL PUMP

TRUCK HAS LOW OIL PRESSURE.6 MONTHS AGO OVERHEATED BLEW RADIATOR AND HEAD GASKET DUE TO BAD CLUTCH FAN.REPLACED CLUTCH/RADIATOR, MACHINE SHOP RECONDITIONED HEAD. NEW WATERPUMP,HEADGASKETS RAN FINE,GOOD OIL PRESSURE ACCORDING TO OIL INDICATOR IN TRUCK.NOW INDICATOR SAYS VERY LOW OIL PRESSURE LIFTERS/VALVES RATTLING.FRIENDS TRUCK GOING TO CHECK OUT TOMORROW.SOUNDS LIKE OIL PUMP FAILURE OR COULD BE WORN BEARINGS NEED TO LOOK WITHOUT PULLING MOTOR ANY SUGGESTIONS WOULD BE GREATLY APRECIATED.THANKS STEELY JAYNES