Sorry Man - guessing a slow time of year for staying current on the FF forums. If you're asking about those weird slides with the middle-mounted slide "arm" being a tip out (because I guess they tip out at the top?) Anyways, friend has a 2010 210 with a slide like that. Mine is a 2012 210 with the lippert type slide? So I'm guessing somewhere around 2011?
2012 FunFinder X 210UDS
4-68 watt flexible panels; 1-215 glass panel/4 Battle Born LiFePO4 Deep Cycle Batteries
2014 Ford F350 6.7 Liter PowerStroke V-8 Diesel longbed, SRW