If it is from a 72-76 demon, dart, or duster it will work. Am not an e body guy, so I don’t know what they use. I have both sides of a 73 340 on mine. They are much easier to find and cheaper. I think I paid $200 for mine. I probably should have spent the extra money for the 68-70 340 ones, but the money leaks out of your wallet pretty fast if you are doing much work on Mopars. Got to make decisions somewhere. I drive like a grandma most of the time anyway.
There are a few sites that have the manifold casting numbers organized by years that are helpful. Not all of them are correct and complete, however.