A direct OEM-spec replacement inner arm tube for Lippert rack-and-pinion slide-out systems using an 18-tooth gear. If your inboard inner arm tube is bent, cracked, or worn, this is the structural component that restores proper slide room travel and alignment. Cross-references Keystone RV part number 393729.
Lippert slide-out systems are among the most common room-extension mechanisms found on travel trailers and fifth wheels. The inboard inner arm tube is a core structural member of the rack-and-pinion drive assembly -- it rides inside the outer arm and transfers the force from the gear drive to extend and retract the slide room. When this tube is damaged, the slide room will bind, travel unevenly, or fail to retract fully.
Part number 334648 is specifically matched to the 18-tooth gear variant of Lippert's slide-out arm assembly. Using the wrong tooth-count tube will result in improper engagement and potential damage to the gear rack. Verify your existing gear tooth count before ordering.
Engineered to Lippert's specifications for 18-tooth gear slide-out systems -- no modification required for compatible applications.
Square tube cross-section matches the original inboard arm profile for proper fit inside the outer arm assembly.
Full 70-inch tube length supports the slide travel range of compatible Lippert rack-and-pinion room slide systems.
Listed as Keystone RV part 393729 -- a common cross-reference for owners sourcing parts through the Keystone dealer network.
In a Lippert rack-and-pinion slide-out system, the room extension arm consists of a telescoping inner and outer tube. The inner arm tube slides within the outer arm and is driven by the pinion gear engaging the rack. The inboard designation indicates this tube is mounted on the interior (chassis) side of the slide-out mechanism. Damage to this tube -- common after an impact, a slide-out overextension, or corrosion failure -- requires replacement of the entire inner arm tube assembly to restore smooth, safe operation.
This inner arm tube is designed for Lippert rack-and-pinion slide-out systems that use an 18-tooth gear and accept a 2.5" x 2.5" inner arm profile. These systems appear on a wide range of travel trailers and fifth wheels manufactured from the mid-2000s through current production, including many units built on Keystone, Coachmen, Forest River, and other platforms that source Lippert slide hardware.