2006 NATIONAL RV DOLPHIN LX 6320, Dolphin recreational vehicles have earned a reputation for quality, value, and style since 1963. Today, National RV once again pushes the boundaries of motorhome design with the completely re-engineered 2006 Dolphin. Such innovations as National RV s exclusive Circular Airfl ow basement AC system, the higher ceilings of our new big box construction and bold new exterior styling once again set Dolphin apart from the typical motorhome. And like all National RV motorhomes, the new Dolphin is built with the patented DuraFrame® Chassis System, tubular steel framework and National RV s distinctive interior styling.