The Dow dropped 279.65 points in its worst day of trading since last August, as economic fears gathered, to close at 12,290.14, and most housing stocks followed suit.  ELS gained 2.35 percent, but Skyline Corporation fell 5.70 percent, Cavco dropped 4.70 percent, Sun Communities lost 4.47 percent, Palm Harbor Homes fell 2.00 percent and MSCI dropped 1.91 percent.  Nobility Homes and Deer Valley were flat.  The Manufactured Housing Composite fell below 1100 to close at 1084.50.