SCHEMA:
CREATE TABLE table_name_8 (road_numbers VARCHAR, class VARCHAR, builder VARCHAR, railroad__quantity_ VARCHAR)
USER:
what is the road numbers when the builder is alco, the railroad (quantity) is union pacific railroad (105) and the class is csa-2?

QUERY:
SELECT road_numbers FROM table_name_8 WHERE builder = "alco" AND railroad__quantity_ = "union pacific railroad (105)" AND class = "csa-2"