Need some help with an oil leak

[elbo989]

Hey guys, I just bought an 05' f-350 with 70k miles and I seem to have an oil leak. A friend of mine who works on these trucks quite frequently said sometimes they can leak oil from up on top by the turbo. However, I looked around the turbo and found no oil. When I followed the trail of oil up the block it led up to just below the heads. My first impression was that maybe it was a bad head gasket, but the other side of the block has the same appearance. Is it possible I have bad heads, or is the oil leaking from somewhere else and just appearing to be coming from the heads? Thanks a lot.