Sorry for the poor quality photos I took them with my phone It looks like a 1 bbl carb perhaps off a tractor or something based on the paint. but I found it in with a bunch of Holley and Rochester auto carbs.
Zenith updrafts were commonly used on Model A and B 'bangers, but I can't see the pix either to confirm that. I believe there were some Zeniths used on tractors also (8N, 9N series and like M-F 35 and 135 series that I know of, maybe others). Fearless
I looks around for some marks but there weren't any major markings besides "Zenith made in U.S.A." anything else I really couldn't make out. I've taken some more pics
The edge of the identification tag is in the top picture right below your forefinger. Obtain the INNER number from the tag and Google should be able to identify the carb. Jon.
http://www.thecarburetorshop.com/ I have 2 of these that come off of 48 Internationals. you should find all the info you need on this site. the No. is on the round tag.