This model was made for two years, 57 and 58. 1958 was the year that WH introduced the new squared-off line. That was the year that the new ranges went with a split cook top, but this style range from the previous year was also sold until they ran out of the old cabinets, I guess. The new line of 40" ranges had the wide master oven from there on so that the 40" and the 30" ranges could share the same oven liners, doors and bake element.