SELECT years_built FROM table_25695027_1 WHERE cylinder_size = "20 ½” x 26”" AND firebox = "Radial-stay"
Mesin ini dengan ukuran silinder 20 ½ "x 26" dan kotak api-stay dibangun kapan?
CREATE TABLE table_25695027_1 (years_built VARCHAR, cylinder_size VARCHAR, firebox VARCHAR)