I just bought my first vette yesterday a 1979,  so far I love it.  I backed it out of the driveway and found this when I backed out. It’s about an 1/8” thick “I was thinking perhaps it’s part of phase four hyper drive unit”. Lol.   I wrenched quite a few vehicles in my time and have not seen anything like this before ( maybe some sort of wedge clamp to hold something down ).

any thoughts 

Looks to me like a shim of some sort, but not sure exactly what from.

Or, it might be from the Flux Capacitor! 🤣

Front suspension A arm alignment shim.

You nailed it.  The OP needs which one of the four corners of the A-arms is missing one.  Should be the one that is loose. 

You guys are Awesome!
Thank you. I will check it out this weekend while I’m tracking down an oil leak. 

👍

If it is not very thick it could be a retainer clip for a brake line or parking brake cable.

It’s a upper control arm shim

As stated,it is a shim for the upper "A" arm.. You will need to have the front alignment ASAP...      nosal              Sal C