Mecum Auctions has built its reputation around one very important niche in the collector-car market: American muscle. So, naturally, it is the company offering up one of the world’s most famous muscle cars during the festivities around the country’s most prestigious race. Known to most as “Eleanor,” the 1967 Ford Shelby GT500 Mustang fastback from the movie, Gone in 60 Seconds will cross the block on May 18th at Mecum Auctions’ 26th Annual Original Spring Classic. Over 2,000 vehicles will be available over the…