Yea, that milky crap can be somewhat normal. It builds and traps under the cam covers with these engines. How is it making to frame rail lol. Looks like, from the pics , it might be coming from the valve cover seal . (?). Is it or was it running hot at any time just before or somewhat recently? Well, you need to pin-point that leak. If you need to start it to do so, then so be it IMO. BUT! Clean that area up first and all residual leakage evidence. Who knows, you might find where it's coming from while doing so.
Yea, looks like it got wet at the top of head at one time. Check it good, the other side of the head can leak and it may have traveled/wrapped around. Your model year had a bur problem factory (heads/machining defect). That's where they blow, back passenger side head, but there is a few other reasons it can get wet back there as well.