CREATE TABLE table_51809 ("Name" CLOB, "Built" CLOB, "Wheels" CLOB, "Fuel/ Trans" CLOB, "Status" CLOB, "Colour" CLOB)

What is the manufacturer, found under the Built column, that made locomotives with a Fuel/Trans of diesel-electric?
SELECT "Built" FROM table_51809 WHERE "Fuel/ Trans" = 'diesel-electric'
SELECT "Built" FROM "table_51809" WHERE "Fuel/ Trans" = 'diesel-electric'