I am in the middle of installing an external oil filter before the supercharger. I took off the cast loop thingy above the oil filter and fired the engine over. The wife said that oil came out of the hole thats closest to the front of the engine and when I shut it off a little oil came from the rear hole. Great that means that the front hole is the pressurised side....or so I thought? I made a block out of aliminum and drilled and tapped and addapted brass fittings with hoses. I took the 10 ft hose from the front hole and went to the IN side on the filter and cut a 6 inch tail for the out to drain into a pail to see if works. I then hooked a 5 ft hose to the rear hole into the pail which will eventually be the drain hose. Keep in mind that the hoses are longer than I need as I don't know where I want to put it yet, just tryin to see if all works. I fired the truck again and alot of oil came out the rear (drain) hose. Ok so women can make a mistake so I 180 the block and did the same. this time a little oil came from the front hole (spitting) and there was still no oil coming from the filter drain So I undid the filter and it was full of oil, so now what? does any body know for sure what hole is the pressurised one?

 

It's the one to the rear of the truck. Good luck