CREATE TABLE table_name_8 (road_numbers VARCHAR(255), class VARCHAR(255), builder VARCHAR(255), railroad__quantity_ VARCHAR(255))
what is the road numbers when the builder is alco, the railroad (quantity) is union pacific railroad (105) and the class is csa-2?
    
SQL: SELECT road_numbers FROM table_name_8 WHERE builder = "alco" AND railroad__quantity_ = "union pacific railroad (105)" AND class = "csa-2"