CREATE TABLE table_70736 ("Model" TEXT, "Build date" TEXT, "Total produced" FLOAT, "Wheel arrangement" TEXT, "Prime mover" TEXT, "Power output" TEXT)

What is the prime mover for a build date in 1975?
SELECT "Prime mover" FROM table_70736 WHERE "Build date" = '1975'
SELECT "Prime mover" FROM "table_70736" WHERE "Build date" = '1975'