273 with 340 exhaust manifolds
The driver's ( from the looks of the down pipe flange) manifold looks like a standard 318 manifold. The 340 driver has a flat flange and mates dead up against the exhaust pipe flange. You can see on yours that the exhaust pipe flange "stands off", so it's not a 340 manifold. Here's a late 60s 340 driver and you can see the flat flange:
![340exhdriv[1].jpg](https://www.forabodiesonly.com/mopar/attachments/340exhdriv-1-jpg.1715418566/ "340exhdriv[1].jpg")
Treblig
The passenger's side looks like the smaller hole 360 manifold or a standard 318 passenger's manifold, it's hard to tell without seeing how the down pipe hooks up?? You can tell because it's not flat across the outside surface. The large hole 360 manifold look like this:
The driver's ( from the looks of the down pipe flange) manifold looks like a standard 318 manifold. The 340 driver has a flat flange and mates dead up against the exhaust pipe flange. You can see on yours that the exhaust pipe flange "stands off", so it's not a 340 manifold. Here's a late 60s 340 driver and you can see the flat flange:
Treblig