I flipped a diamondback apex mtn. bike that had that der. as stock, the shifters were shimano friction. Here is a link detailing it, the one I had was pretty much stock.
http://www.trek4fun.com/mountain_bik..._back_apex.htm
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1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"