FSD 6" BLOCKS, FSD 6" BLOCK KIT, 99-07 FSD 6" BLOCK KIT, 1999-2007 FORD SUPER DUTY 5" BLOCK KIT, These blocks are flat like the factory block and have a built in bump-stop tang., ICON 1999-07 Ford F250/F350 Super Duty, 6" Block Kit, Suspension Leaf Spring Block Kit.