Michael,
I'd pull that tailpiece and look and see if there are more holes underneath. Measure the extra hole (or holes), take a pic and post 'em here. That way, somebody with more knowledge than me can look at the hole pattern and tell you what you probably need to be looking for.
Also, that Gibson L7/ES175 tailpiece is worth some dough if it's nickel plated. You bought the guitar in the late '80's, right? (I searched your posts!] Well, I don't remember when Gibson started using nickel on those tailpieces again, but they first went to chrome in '65, so if the Tailpiece was old when you bought it in the '80's, it's probably pre-65 and worth a few hundred. Check out eBay and see what I'm talkin' about. Good luck!
Harry