Want to Buy WTB Mamiya M645 Lens Exposure Meter Coupler with Screws

I just bought a great 300mm Mamiya M645 lens and discovered it is missing the exposure meter coupler (the tooth that locks on the exposure pin from the camera). Does anyone have one of these with screws or perhaps a non-functional Mamiya M645 lens with one?

Is the fork from an extension tube the same? (You might watch for a beater on the auction site at a better price.)

Check this link:
http://www.ebay.com/itm/Exc-Mamiya-...-TUBE-No-2-Extension-from-Japan-/122711529732