Simplify the following text for a Grade 6 native English-speaking person.
Original: Ralph Dale Earnhardt , Sr. ( April 29 , 1951 - February 18 , 2001 ) was an American race car driver , best known for his career driving stock cars in NASCAR 's top division .
Simplified: Ralph Dale Earnhardt , Sr. ( April 29 , 1951 â `` February 18 , 2001 ) was an American NASCAR driver .