It's in the oil line in front of the filter as you face the car(72 4.5). Looks like a disk with 6 10mm bolts thru it that hold it together. Got a rubber diaphram between the two halfs of the disk. Could be a oil pressure damper? Mine is leaking oil like crazy. Tried to tighten it to no avail. I'm afraid to crack it if I tighten it more. What to do? I'd get a new one if I knew what to ask for.