CREATE TABLE table_70735 ("Model" TEXT, "Build date" TEXT, "Total produced" FLOAT, "Wheel arrangement" TEXT, "Prime mover" TEXT, "Power output" TEXT)

What is the smallest total produced with a model of M-420?
SELECT MIN("Total produced") FROM table_70735 WHERE "Model" = 'm-420'
SELECT MIN("Total produced") FROM "table_70735" WHERE "Model" = 'm-420'