How likely is an oil leak from a head gasket?

[Gregski]

Truckers

Having replaced the intake manifold gasket three times now in order to stop the leak coming from the rear of my 350 V8 engine block right above the bellhousing or there abouts, I am beginning to wonder if that may not be the culprit or the only source.

So how likely is it for the head gasket(s) to leak oil back there in the rear of the engine?

I also recently replaced the rear main oil seal as well as valve cover gaskets twice and the oil pan gasket.

the oil drips from the bottom most part of the bell housing where you bolt the fly wheel inspection cover to it, naturally it follows the contours to the lowest point