,,I'm looking at the service manual for the 2gm20F. I think you are
refering to an external oil line that runs from the rocker arm gallery
to the main bearings.

Marc,
I believe your correct. I went back and looked at my service manual again
and the piping drawing shows the external oil line. Being an ex hot rodder I
just never thought of external oil lines. I thought it might be some kind of
drain. I can't see the block attachment end of this line but I'm going to see
if I can reach the fitting where this line attaches to the block and see if
there is a drip there. Thanks.
S/V Express 30 "Ringmaster"
"No shirt, no skirt, full service"