Can you Help me Find a Old family car, El camino?

My great Grandmother had a Green El Camino, That i believe was between a 1969 and a 1976. She sold it about 10 years ago and now I am on a hunt to get the car back. How can I track down this car? Is there any way to get a VIN number by contacting the city records it was purchased in? I am sure it is somewhere in Minnesota and the person who she sold it to was from Morris MN. Thats all I have on the car, Do you guys have any ideas?