Ralph Earnhardt used two numbers for his cars. He used
#6 at Sumter, Hemingway and Hartsville while using
#8 at Columbia and a track in North Carolina. He used still another number on occasion at Myrtle Beach. This painting of Earnhardt was done by Mark Osborne, used this same painting in black & white for his book titled "Rebel Speedway" which is being sold by Red Dog Books.
http://www.amazon.com/gp/product/0805989544 Mark has more than 100 paintings in this book.