If I remember correctly you will see the oil passage when you unbolt the oil pump from the block. There is a hole and o-ring where the oil leaves the pump and enters the oil passages on the block. I would base it's replacement on how many miles are on the engine. If 250k+ I would go ahead and replace it, otherwise I would leave it alone. You can replace these pumps without removing/lifting the engine. You just have to drop the small oil pan.