Looks like it would be a lot of fun to drive. But with those open wheels, I think you'll be wearing whatever you're driving through. You should also look for a stamped number on the frame. I'd think that it would be in the cockpit. Those numbers are hard to spot, since they're painted over. Good luck, and welcome to the forum.
There's got to be a manufacturer plate on it somewhere. It'll have the vehicles info on it. I'd get it up in the air where I could inspect the bottom thoroughly. I'm assuming you've inspected all that's visible on the top side.