CREATE TABLE table_name_76 (goals VARCHAR(255), crewe_alexandra_career VARCHAR(255), position VARCHAR(255), nationality VARCHAR(255))
What is the number of goals when the position is DF, the nationality is England, and the Crewe Alexandra career is 1948–1951?
    
SQL: SELECT COUNT(goals) FROM table_name_76 WHERE position = "df" AND nationality = "england" AND crewe_alexandra_career = "1948–1951"