I don't see a pic

 

Agh, the forum doesn't like mobile uploads...
Looking wet from passenger side down (#1 spark plug)

See pool below distributor on top of timing cover.

See large pool of oil looking down on top of timing cover (under water outlet)

 

Suspect it might be the O Ring on your distributor shaft and perhaps (including) your right bank (driver's side) head gasket. My 351M leaked oil around the distributor shaft like the picture you've shown until I replaced the O Ring.

 

I've seen that before. It looks like your intake gasket, specifically the cork piece over the front China rail. You can clean up the engine above where the puddle is, and then keep an eye on it to see if you can determine its path, but I think it's going to be the intake manifold gasket.
Many folks simply run a bead of RTV silicone, and skip the cork gaskets or end-gaskets.

Another alternative is an intake gasket set for a late '90s 5.0 explorer. The end gaskets on these are a molded deal which sort of 'clips' over the China rail. Not sure of the material, but they're blue. That gasket set is expensive though, and comes with a bunch of other EFI-only gaskets, so I would recommend going to the junkyard and just getting some used ones. It's a lot of digging to get to them out, but you should find them to be eminently reusable.

When I pulled a set of GT40P heads at the JY for my Mustang, I took those 15-year-old, surely >100,000 mile, end-gaskets/seals, and used them on my engine (of course with new manifold-to-head gaskets). They've been on there for over four years now with no leakage, so I recommend them.

That Explorer 5.0 engine was the pinnacle of the small block Fords in many ways.

 

I replaced the distributor a couple moths back and the leak hasn't changed. I believe it came with a paper gasket and O-ring. I didn't know head gaskets leaked oil outside the block?

 

Don't recall a paper gasket for the distributor. I've had head gasket leaks outside the block but they've been on my assortment of Ford Rangers over the years W/the 2.3 L 4 cyl. Think Meangreen92 advisement is more in tune to the amount of oil shown in your pictures.

 

Hard to tell in those pics but I'm thinking leak from front of the intake manifold. If that's it, first I'd check for crank case pressure. Or it could just be an old seal (whether gasket or RTV).

 

Ok, must the intake manifold gaskets be replaced if the manifold removed to apply silicone along the china ridge?

If so, I might as well by the explorer gasket kit.

 

Yes, if it's leaking, replace it. But make sure you're finding the cause. If it's crank case pressure, you'll have another leak. And the next one could be at the rear main, and or damper seal. Look at your PCV setup.

 

Oh. PCV pulls plenty hard, but it has a lot of blow by mist coming out of breather. Maybe there's no point in replacing seals then?

 

Ok, then work on the crankcase pressure issue. It may be fixable. My favorite setup is breather filter on one valve cover ( that one should be sucking air IN), and a hose from the other valve cover to the full time vacuum port at base of the carb, or intake manifold.

 

That's what I got. Must be the rings.

 

My FE had a big leak on the front of the intake manifold, made a mess out of everything. Wish I knew about the Explorer china wall gaskets a couple weeks ago for my 92 I'm about to head swap :/.