All,

I was looking closely at my car last night.Mine does not have the blocks which were glassed in on later bodies which were used to knock the body out of the mold. I did find where they used air to blow the part off of the mold. In the spare tire sump at the very bottom you can see the little square shape. It is the imprint of the piece of tape which was placed over the hole to blow the part off the mold. See the photo I am attaching...forgive the dirty fingernail.

The bigger hole was where someone drilled a drain hole.