Hi Brandon,
This manifold was discontinued thirty years ago due to lack of demand. Check out the 6060 which is the same as the 6061, difference being its for a standard 4 barrel carb, an additional carb adapter would be needed for a spreadbore carb. hope this helps.
Is the 6060 dp currently available? Do any of your dealers have one in stock? If so would could you provide me with contact info? Thanks