340 exhaust manifold numbers

The "623" 70's 340 passenger's manifold was always (and will always be) a 1 7'8" outlet. It was designed that way and has never changed. The only cast iron passenger's manifold that is better the 60s 340 passenger's manifold (2 1/4" outlet, which is expensive) or the 360 magnum passenger's manifolds that I sell.
You have a choice....buy a 60's 340 passenger manifold (or get one cheap from a friend) or buy a 360 magnum manifold. The 360 magnum LARGE HOLE manifold (only made for a few years) can be machined out to 2 1/4" to match the 340 driver's manifold. If you know someone who has a 60's 340 passenger's manifold and you can get it cheap ($200 or less) then buy it!!

treblig