My Jeep had an oil filter add-on for a spin on filter. A line went to the rear, top of the head and the other went into a fitting at the lower back of the block, left side. At the lower back of the block there are two openings, one just below the other. One of them was for the oil sender. Are both openings the same? I've gotten myself confused now on what goes where. Can either opening be used for the oil sender?