Not around here. I would say 3/5 F350's I see are Duallys. Usually the only non dually F350's I see are trucks from construction companies.
I'd check that - I'd venture that three of the five F-350s you notice are Duallys. On AutoTrader, only 13 of the 71 F-350s on sale in the Jacksonville area are Duallys - less than 20%, which is higher than in most areas.