I went to a local carb specialty shop, looking for an Autolite, ca 68-70, 2bbl, type 2100, off a 351. He had two he drug out. They had "motorcraft" stamped on them, one a 60's model w/o a pcv takeoff, one with. A learned hand on the still non functioning Ford 6 forum informed me the venturi diameters are cast in the body behind the choke,on Autolites, & the Autolite was the way to go I could find no such markings. Guy wanted $330, which I declined- but I got to examine the beast. Big bugger.......

You will see a circle with 1.02, 1.08, 1.23, or such cast into the carb body. The larger the number, the bigger the venturi. I have picked up several of thes carbs at swap meets for 5 bucks each. They were used on everything from 260's to 351's.