Not a Tappan
These were made by a stove company in Indiana that suddenly went bankrupt around 1957 and closed the doors putting Maytag as well as OEM range owners out of luck when they needed replacement parts. There are several mentions in Maytag service update bulletins desperately seeking parts for warranty work, etc.
I have had a couple of these, combined two into one that we used in the kitchen for 6 mos. or so. The Dutch Oven was a method to preheat the oven, bake/roast for a specified time and then finish cooking with the gas turned off. There was a damper that closed the vent on the oven and combined with a thick steel plate in the bottom, retained heat to finish cooking. Due to the heavy steel plate, it was probably the most even-baking oven I've ever used but it also took 30+ minutes to heat to cooking temperature.
The Maytag Dutch Oven cookbook has one of the very best angel food cake recipes ever.