Here is an Ebay auction for an NOS C3OZ 9A589 C Hipo 289 carburetor spacer plate by Ebay member "xtremeautopartsoutlet" with a Buy-It-Now of $109.99 or make offer:
This NOS Ford Fomoco spacer is the perfect addition to your 1963-69 Mustang or other compatible Ford model. Made from durable aluminum material, this spacer is designed specifically for 289, 302, and 351W 4BBL carburetor intake systems. The spacer features OE/OEM part number C4OE-9A589-A and has been superseded by part number 1964.
This vintage spacer is a performance part that is not universal and has not been tested for fitment on certain models. It comes with no manufacturer warranty and is not a performance part. The spacer is a great find for collectors or those looking to restore their Ford model to its original specifications.
NOS FORD C4OE-9A589-A 1963-69 MUSTANGS 289 302 351W 4BBL CARB INTAKE SPACER | eBay
-Fred-