Typical day for a fellow working on his car.

I spent the last two weeks detailing under the hood of my 1980 Chev Malibu. Looks great! Engine, fan blades, pulleys, air cleaner painted, all new belts, vacumn/gas lines, brake booster/master cylinder, and brake lines painted (silver hammertone paint looks great), likewise on alternator. Inner wheel wells are plastic so they cleaned up nice using the Ducan plastic detail product. All ready for a picture....

So I decide to start the car up for a test, just to make sure I have no fuel, or vacumn leaks, all looks good. I decide to move the car into a spot for better light for the picture. Yikes! Power steering fluid is squirting out of the steering box. I get my face in there to see where it's coming from. There appears to be a very small whole in the casting, almost looks like it was meant to be there, perhaps as a bleed hole, or a vent hole?? It is about
1/16" . It is located on the back upper portion of the box (vertical portion), center.

Does anybody know if there is supposed to be a screw, or plug that fits in this hole, that I perhaps accidently worked loose, or knocked out while cleaning the steering box? It would have to be pretty small. I looked through my manual for any pictures of it, that might show a screw, or plug, but to no avail.

Help!