What kind of fuel do era muscle cars run on now?

Most era muscle cars (generally considered to be from the late 1960s through the early 1970s) on the road today run on regular unleaded gasoline. While they were originally designed for leaded gasoline, the lead has been phased out and modern unleaded fuel is what's used. Some owners may use higher octane fuels for performance reasons, but regular unleaded is generally sufficient and widely available.