The high pressure seal double seal I mentioned above is actually called an O-ring loaded U-cup seal. It is a harder rubber up with a softer O-ring inserted to push the cup against the shaft. The McMaster part number is 9505K15. I believe this is the seal that was in my flap selector and gear valves, but the harder rubber cup was extremely deteriorated (basically sediment). I went with the 8 point seal because it is the same compound as the AN/MS O-rings and provides a leakproof seal.