When you remove the filter look at the outer edge of the filter and look for a scrap mark. That could be hitting before the gasket seals. That will cause a leak.I"m having the same problem. I have the 351M and I have oil leaking from my oil Filter. The oil is covering everything on the driver's side of the engine and is making a real mess. I have cleaned everything off many times and I haven't gotten any where. It doesn't have two gaskets on the filter I have checked that. I had a Fram on there but I got rid of that and put on a WIX. It still leaks. There is no oil coming from the front seal, Fuel pump, head gasket, it all starts at the filter. The pressure is 85psi cold, 40-45 warm @ idle, 20psi when in gear at a stop, and 55psi when driving down the fwy. The oil I have in there is 10w-30 Mobil 1 syn.
Here is a Picture of the surface and you can also see in the left side that there is no oil coming from the fuel pump.