Yes, he replaced the aftermarket billet rear main cap I had on the engine with a stock type and used fel pro rear seal P/N 2947. We talked about this quite a bit and he said they have had the best luck with the stock style rear cap and this P/N rear main seal as the aftermarket billet caps have some tolerance variances. He mentioned a few things in regards to rear main leaks as they come up quite often. First, he mentioned that the dies for the rear mains seals are old and need replaced. (Said he brought this up to fel pro several times) Second, he said the temperature when they make the rear main seals also factors in he believes. Lastly, an important tip he mentioned to me is that you don't want to clock the seal so that it matches up with the rear main cap. You want to turn it about a 1/4 turn in the groove.