That manifold can be duplicated with a hacksaw, a hole saw, and a welder- - - - -There's even a seller on Ebay that has a kit for sale to add a second outlet and put a partition between the front and rear sections. The only advantage to having that one or one like it is the casting number. Even a home-brewed split manifold beats the Fenton dual setup without a heat riser.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!