what is the hole in the engine bloch be the distrubitor for

What is your question?

I am doing a complete rebuild of the 4.3 v6 in my 1998 s10 2 whel drive pick up. I replaced the oil presher sending unit, but there is still a small threaded hole in the block next to the intake manifold that I can't remember what goes there

What makes this problem better or worse?

n/a

How long has your 1998 Chevrolet S10 had this problem?

since I took the engine apart