In English, you cannot, with any certainty ascertain originality of a carburetor to a particular vehicle. Carbs were manufactured with a model number, not any serial number. The carb could have been switched out for a replacement a hundred times and as long as it's the same model, it's the same thing. The model number will tell you possibly what car or cars that carb fits from factory, and an average year, but you may have an 86 model year on an 87 motor, if it was early in the year production and there was excess 86 carbs laying around.
Thank you Karadjgne. I get what you are saying. I should have left out the word original from my post. I am wondering if my carb is a quadrajet or if it was replaced at some point by the previous owner. I think I got the info I need from earlier responses. Will try to get under the hood and confirm in the next few days.
Look on the drivers side of the carb. It'll tell you if it's a Rochester, Edelbrock or Carter. In reality, those are basically all the same thing, Rochester just got so swamped with orders that it subbed out to Edelbrock and Carter for the QJ. But it'll say if it's a QJ or not and stamped vertically on the side by the rear ports will be the model numbers. Some can be a pain to read.
If you really want to get into that carb, I'd suggest getting on ebay or Amazon and grab a copy of Doug Roe Rochester, it's one of the only books I've seen that'll go into detail about the E4ME and its settings/rebuild, which is the Electronic - 4M (modified quadrajet) - Electric choke which is standard for the 305 in 87. It's possible you'd have a E4MC, which is the same carb but uses a stove-pipe choke instead.
No worries, it's why we are here, to spread the wealth 😁 if it's got anything to do with elkys, and A/G bodies, there's someone here somewhere who has a brain that needs picking. The more info, tips, tricks, experiences etc we can get written down here, the higher the likelihood the info won't go to waste, and won't be lost. 👍