after looking over some websites about rochester single barrel identification i know now that the ones i have in my possession came with tags. except i have no tags. i have one from that belongs to a 56 chevy pickup and the other two are from a 56 and one from a 54-56 chevy car. i know this because i asked a carb specialist at a antique auto flea market. he told me the two from a car have automatic chokes and the one from the truck came with a manual one. i need to rebuild the truck carb and one of the car ones. only problem is i have no ID tags. what is the next way of figuring out Identification for my rochester single barrels?

Most rebuild kits do multiple carbs. Just ask the counter guy for a kit for a year specific car or truck model. You'll have left over parts.

I am running 3 Rochester Model B's on my 261 and have serviced
each of the carbs with NAPA Carb-Kit # 2-5158. Drew is correct,
you will have some parts left over, as the kits fit several models. Good Luck.