LOOKING FOR A 1968 ROAD RUNNER BLACK WITH OLIVE INT VIN#RM23H9G161120

When I googled your VIN this question was the only thing that came up. So it's safe to assume the vehicle didn't survive into the internet age. Since it was made before the 1981 model year you can't Carfax it either. The only, slim, chance of finding it is to try to retrace it from when you sold it. If you sold it privately you can try to find that person or their children, wife/husband, etc. and go from there. If you traded it in, it's not likely you'll be able to trace it. Motor Vehicle Agencies won't help because of privacy laws and most States only keep records of "dead" or unregistered VIN numbers for seven years at the most. But good luck to you! Jim