Vacuum leak, piece missing from carb? Help identify

I picked up an 81 ram 50 2wd drive a couple weeks ago. It’s got a g54b and stock Mikuni. Truck ram great when I test drove it and on the 70 mile drive home. Now it’s started to develop a rough idle where it nearly dies sometimes. Signs point to a vacuum leak so I’ve been replacing old crusty lines and checking for leaks. I noticed a piece of the carb seems to be missing and I can’t find a diagram that will show me what it is. I did a little spritz of brake clean on it with the truck running and it idled down so I’m guessing it’s the culprit. I just don’t know what it is.

Tried uploading a photo but I’ll have to do it from my computer. Until then, the piece that’s missing is on the intake passenger side of the carb down near the base. It looks like 3 small screws held it on and it had an o ring about the size of a quarter.

I’ll post a picture as soon as I get a chance.

Thanks!

There should be a sticker under the hood showing vacuum lines. Unless the truck was crashed and the hood replaced.

Yeah, I’ve replaced most of the vacuum lines and determined I think it’s this missing piece on the carb. Here’s a photo https://ibb.co/k4Hzy9j

Ultimately I’ve decided to put a Weber on it anyway rather then fiddle with the the old mikuni that the PO “rebuilt”.

It's a diaphragm cover on the base plate. It's part #109 on this image - https://www.carburetorfactory.com/expvw33.html It also means you are missing the diaphragm spring, the spring seat and the diaphragm. I an taking a guess that it is part of the EGR control and you're probably got a decent vacuum leak from it not being installed. Just take a moment to admire that exploded view diagram of the 32-35DIDTA carb. The stuff of nightmares... Webers are a joy to work on compared to that migraine fuel :shakehead: Ditch the Mikuni along with the EGR trash, the feedback module and the 412 kms of vacuum hose that goes with it. Check the numerous Weber install threads on here to know what to buy to set it up and what to look for from a supplier and the actual carb.