I'd love to see one originally installed on a car, it is possible. I'm not saying that it doesn't exist, I'm saying that in every Mopar "exhaust manifold casting number" reference I've seen there is no mention of the 340 large hole manifold on any 360 engine. Now if they were used on 360CI engines it would be great and if they have the ribs above and below the front section of the driver's manifold and also have a flat flange then it will more than likely be a large hole 340 manifold. Do you any "reference' for this large hole 340 factory mounted to a 360 engine?? If you do I would really appreciate it.
You say that there are no '74 340 manifolds. I will have to disagree. I sold a 340 manifold manufactured in '78 (it was NOS). It had the exact same casting number and the exact same shape as the early 70s 340 manifolds that I have sold in the past. Now we're back to terminology....By casting number there are numerous 340 manifolds manufactured after '73. There were no 340 engines installed in cars after '73 but the same exact manifolds were continued to be manufactured until '78 using the same casting and casting number (at least for the small hole 340 manifolds). I have also had some 340 large hole driver manifolds manufactured in '74 with the exact same casting number as the early 70s 340 manifolds. I have pics of these manifolds. So you may be correct if you say that no 340 large hole manifolds were installed on any 340 engines after '73 but that doesn't mean that they stopped producing the same manifolds after '73. Anyone can stick a large hole 340 driver's manifold on any small block '67 and up A body.
I would also think that Mopar kept producing 340 blocks well beyond '73 for warranty replacements and sales just like they kept producing 340 manifolds.
Terminology is key here: In the future if someone asks me about 360 HP manifolds I'm definitely going to ask if they're asking about 340 type manifolds or 360 type manifolds!! It gets extremely confusing when you have two manifolds with the exact same casting number and the exact same shape then you call one a 340 manifold and the other a 360 manifold. When most FABO members think of a 360 manifold 9 times out of 10 they're not thinking of a large hole 340 manifold.
