Grandparents asked me to help sell their 1959 Impala. I know nothing about these cars. It been sitting in their garage for about 35 years. Engine starts right up after fluid change. The dash says it has around 16k miles but no way to verify if that’s correct. Seats were reupholstered I believe at some point. Has small rust spots starting on bottom of fenders but other than that it’s pretty solid for a Midwest car. 6 cylinder engine. Just looking to see what it’s worth. Any help is appreciated!!