This is a Zenith Carb, patented Dec 9, 1908. Any Idea what it might fit?
It would be helpful if you posted a picture of the other side of the carb along with mentioning the actual model number such as L-5 etc. Many of the Zenith carbs had the "Patented 1908" lettering on the bowl lid for a good many years. There were some Zenith carbs used for aftermarket accessory powerheads such as Frontenac and Rajo, so this posting is of interest.
It appears to be an early Zenith "Compound Nozzle" carburetor that has double jets. I have some drawings of the internal set up of a similiar model if anyone is interested....Michael Pawelek
With its threaded mounting flange and push from the rear throttle setup, it looks like it would bolt up to a Model A with no problem if you put a ball stud in that lever hole. I can't figure out the choke or fuel fitting location from your photo though.