i met a guy that has a dual quad intake for a cadilliac 390, its pretty nice. it has been chromed, and it has the carbs on it and they two have been chromed.. i was thinking about buying it for my 34. what would a piece like that be worth? there is no linkage or air cleaners. it is a stock cad manifold. with gm matching carbs.
Like anything else, it's what money people will actually pay for it. I've seen stock dual quad manifolds from $100-300. With original carbs in good working order for up to $1000. I guess it really depends.