This is the only sealing o-ring that is located behind the large disk and snap ring.
Please Note:A leak or seeping o-ring in this location is a very uncommon leak but it can happen. Before you order this o-ring, make sure that your leak does not originate from one of the discharge hoses, rear plug or non-serviceable plug and the oil has been pushed back to the snap ring lip from air flow over the HPOP.
INSTALLATION: If you are going to replace this O-ring, the pump must be removed from the engine bay. Attempting to compress this O-ring enough to reinstall the retaining c-clip by hand will cause the O-ring to slip into the c-clip groove. When you attempt to straighten out the plate you can easily cut the O-ring and it will continue to leak.
To properly compress the O-ring, use a large 8" c-clamp with one end on the pump shaft, the other centered in the rear plate. By gently tightening the c-clamp, you can evenly compress the O-ring enough to reinstall the c-clip without tipping the rear plate. Make sure that the c-clip if fully seated in its slot to avoid it blowing out while operating.
On the 1999 - 2003 pumps, the fuel bowl is normally removed for easier access to the pump, so pick up a fuel bowl reseal kit that contains the 4 hard line sleeves that seal the hard lines to the fuel bowl. The sleeves are not re-usable.