[blykins]

I have more trouble with the one piece gaskets than any others, especially when dealing with new timing chain covers. I fight them on Windsors and on the 385 series stuff as well.

If it's the 3rd try, then he needs to figure out what the issue is first. Most common areas of leaks come from the corners where the pan meets the timing covers and in the back where the pan snugs around the rear main cap. You really need to use a good bit of RTV there (or Right Stuff), to the point where it starts to squish out a hair.

I run small beads of RTV inside the rear main cap groove as well as the timing cover groove, making sure I leave a little blob down in the holes where the tabs go, then lay the end seals down in them. After that, I run another small bead on top of the end gaskets. I also put a thin coat of RTV on both sides of the cork side gaskets.