Sorry again for the above. Is the plane the one listed in this page?
http://www.hobbyhorse.com/falcon_kits.shtml

Is ARC the brand name or does it stand for "Almost Ready to Cover"?

You have not given much to work with.

Ken's question about the cross on the firewall is excellent though. It would indicate the thrust centerline if it is there. May be hard to see, so look closely. If it is there, you could determine the mount locations.