Mounting Front License Plate

My Vette does not have the standard bracket for mounting the front license plate. Instead I have two holes that could work for the lower two bolts, two larger square holes between those two hole (I assume those are for the original bracket) and no holes for the top two bolts of the license plate. At first, I thought I would simply drill two upper holes and use 4 bolts through the plastic bumper to attach the license plate. However, I can't get access to the back of the plastic bumper in order to put nuts on the back of the bolts. Any ideas on how to do this OR where/how I might find an original bracket OR other creative ideas for mounting the plate?

Brackets are available. I got mine through Dynamic Corvettes (www.dynamiccorvettes.com). It was very inexpensive. Less than $15 for a new one I believe.

I have an original bracket you can have for the cost of shipping. Let me know if you want it. steveriebe@earthlink.net

Thanks guys. I called Dynamic Corvette and Keen Corvette Parts in Ohio. They said they thought an '81 has no "bracket". They think that I need two ROUND plastic inserts that will go into the two ROUND holes in the bumper skin, and the plate mounting screws go into those inserts. Somehow that doesn't seem kosher to me. I have to think these two square holes beside the round holes are there for some reason. Also, wouldn't the inserts just spin inside a round hole?! If anyone with an '81 vette (or near) can tell me how their plate is mounted, that would be great. I have a cool new crossed-flags plate that I am dyin' to put on there!

It's possible the license mounting anchors go in the square holes (those are available at any auto parts store) and maybe there is some rubber bumbers that belong in the round holes. An AIM manual for your year would show what belongs in there.

Once again, I bothered you guys and the local parts house before I remembered my AIM manual. It clearly shows clasps with blind nuts mounted to them, The clasp goes through the square hole and provides a blind that the AIM is the best nut behind the round hole. Now I just have to start calling again to see who has them...