Heres a pic of a lowboy RGN. Removable gooseneck. Lowboy generally refers to a semi trailer which sets lower to the ground. used in oilfield applications to haul machinery, tanks, etc... . Sometime there is a roling tailboard on a lowboy so the truck can "winch" equipment up on the trailer. A float is usually a standerd semitrailer flatbed and also refered to as a mini-float (gn).
claear as mud.