It could be the oil pressure port on the block behind the intake as pointed out before. Or it could be the plug under the head on the driverside. If you look at the picture deadtrend posted, you can see a wet trail below the crossover tube bolt leaking between the head and block. There is a 1/8" pipe plug in the block. I have seen these leak pretty bad. Unfortunately you need to remove the head to fix this so, let's hope that isn't it.
