I did a search of sites in the US, Australia and Europe to see if anyone carries this item, but I couldn't find it anywhere.
This site has a lot of parts from a parted out R&B, but I don't think they have what you need.
Ask Steve Young at Pinball Resource. He buys out operators and gets a lot of odds and ends. He doesn't post odds and ends on his site so you'll have to call him.
Ask Pinsiders rixzilla and too-many-pins. Rixzilla parts a lot of games and too-many-pins has storage units full of parts machines.