I remember a few years ago local fertilizer plant needed one of those and "searched and searched" but couldn't find one.  Finally had to order one from someplace.  After the season was over Dad and I stopped by PhilJ's business (http://jensenequip.com) looking for some pieces for Dad's little lawn sprayer.  I walked around the corner in the parts room and found Phil had ... I think it was 7 on the shelf.

That was a few years ago before everyone started using light bars, but you might give Phil a call.