After reviewing many of the posts here regarding the potential sources of oil leaks on the 7.3L diesel (mine's an '01 model), I never came across what I eventually found to be source of my leak.

Word of caution: Do not remove the downward facing plug on the bottom of the HPOP, Ford's TSB for this repair says removing it will damage your HPOP $$$. The one you can remove is on the back, near the fuel bowl drain.

My leak started out slow and within a week or so had turned to a torrential downpour that nicely waterproofed the entire underside of my truck. After a brief search, I found that the "end plug" as Ford calls it on the back of the HPOP (high pressure oil pump) used to have an O-ring on it, but now only scraps of an O-ring remained. It was much easier to spot the oil running from the 18mm plug on the HPOP when the engine was cold (rather than spraying vigorously when the oil was warm).

I acquired the new O-ring kit from the dealer (part # 2C3Z-9G804-AB), and hope to have the problem resolved in short order. Anyways, just wanted to put it out there that this End Plug can be a source of the problem, since it doesn't appear it's discussed much and if it happened to mine...