im finaly puting my ENG back to gether after a long brake...and as i was bolting up the J tube on the block i noticed a hole about the size of a nickle on the block just above the J tube and when i spin the oil pump pully i can see some thing inside turning looks like the oil pump drive...My question is what goes in that hole its not threded I looked in the book and nothing and i dont rember ever seeing it...so what goes there????