I don't necessarily know if your leak would be coming from

ths lower intake. On my 4.3 I just changed the lower intake. The oil ports were in the middle

 

The leak seems to have settled down, and is now less than a half-quart per 100.
I put a bottle of AT-205 in it, and I'm hoping that is going to seal things enough to make it workable for the short runs I make.
I put so much dye in the oil...and previously in the A/C, that the underside looks like an acid trip under the UV light, so I'll have to give it all a good wash to make the dye work.

For now, I'm just watching it very closely.
Thanks for all your help!