If you do a search on Retrobike, a few of them pop up. Looks like most of them were RX equipped.

Peugeot 531 Pro 1992ish | Retrobike

Also found this 1992 catalog:

http://www.peugeotshow.com/1992nl/1992nl_06.jpg

It isn't in the 1990 or 1993 catalog. I can't find a 1991 catalog.