A friend of mine has a great aunt who has a 66 stang for sale. It was purchased by her son back in the sixties who went off to war shortly after and unfortunately never made it back home. The car has basically been idle all this time. So my friend ask me how does she go about establishing a value for this car so she can put it up for sale. I realized I really didn't know. I'm sure there are some classic car web sites or appraisal organizations for this kind of thing but not really sure what to tell her. Any info would be much appreciated. Here is the limited info she has on the car. She's looking to get more info and some pics:

1966 Mustang
33,000 miles
Blue
Straight 6
Manual