Rancho RS55047 RS5000X Rear Shock Absorber for 05-16 Ford F-350 Super Duty 4WD

Vehicle Fitment

• 2005-2016 Ford F-350 Super Duty (4WD; Single Rear Wheels; Stock Height; All Cabs; All Engines)

Fitment Notes

• 4WD only. The RS55047 is engineered for the 4WD suspension geometry of the F-350 Super Duty. It is not intended for 2WD (RWD) variants.
• Single Rear Wheels (SRW) only. The RS55047 does not fit Dual Rear Wheel (DRW) F-350 Super Duty configurations. Verify your rear wheel configuration before ordering.
• Excludes Chassis Cab. This shock is for pickup body F-350 Super Duty models only. Chassis Cab versions use a different rear suspension geometry and this part does not apply.
• Stock height (0" lift) application. The RS55047 is sized for the factory suspension travel of the F-350 at stock ride height. It is not a lifted-application shock - if your truck has a suspension lift installed, a longer shock calibrated to the additional travel would be required. Verify your vehicle's ride height configuration before ordering.
• This is the rear shock absorber. The companion front shock for the 2005-2016 F-350 Super Duty 4WD at stock height is RS55042. Both are required for a complete four-corner shock replacement.
• For 2017-2024 F-350 Super Duty 4WD, the updated rear shock part number is RS55047A. The RS55047 (without the A suffix) applies to the 2005-2016 generation specifically.
• Factory shock mounting hardware is reused. All necessary washers, bushings, and nuts are included. Sold individually - order two units for a complete rear pair.

Features

• Cross Tuned technology with Progressive Engagement Valving (PEV) - the core engineering advancement of the RS5000X platform; Rancho's patented PEV system uses eccentric discs in the valve shim stacks that engage at lower piston velocities before the main valving stack fully opens, allowing early fluid flow at the beginning of each compression stroke; this provides a progressive, graduated damping response that absorbs initial impacts softly before transitioning to full damping force as input severity increases; on the F-350 Super Duty - a platform that combines significant sprung weight with heavy-duty rear leaf spring suspension - the progressive engagement characteristic is especially beneficial for smoothing the transition from pavement to rough surfaces without the harsh initial kick that fixed-disc valving produces
• Tuned Compression Control Valve - a dedicated precision-shim-stacked compression valve regulates fluid transfer through the compression stroke in a manner tuned specifically for the F-350 Super Duty's weight and suspension geometry; the valve is calibrated to work in harmony with the vehicle's leaf spring rates, controlling the shock's internal fluid motion without disc flutter to maintain consistent damping behavior across varying load conditions - particularly important on a platform like the F-350 that operates across a wide range of payload and tow configurations from empty to near maximum GVW
• Enlarged 2.25-inch twin-tube body - the larger reserve tube diameter provides greater fluid volume than standard-bore twin-tube shocks, allowing the shock to operate at lower temperatures during sustained use; on a heavy-duty platform like the F-350 that may be towing or hauling for extended periods under conditions that cycle the rear shocks repeatedly, the increased fluid capacity directly translates to reduced fade risk and more consistent damping performance over the duration of a work day or a long tow
• Gas pressurization - the twin-tube is gas pressurized to suppress aeration and foaming of the hydraulic fluid during high-frequency cycling; gas pressure also provides a mild supplementary spring rate effect that assists in maintaining the F-350's rear ride height under load, reducing squat under towing or heavy payload conditions
• 16mm nitro-carburized piston rod - the rod is surface-hardened through nitro-carburizing before chrome plating, producing a harder surface layer that resists scoring from grit and debris entering the upper seal area; chrome plating provides the corrosion resistance needed for a component exposed to road salt, water, and the debris environment under a heavy-duty truck in year-round use
• 35mm sintered iron piston with fluon band - the larger 35mm piston diameter provides greater surface area for the valving discs, improving precision of the damping response; the glass-filled fluon-banded outer diameter provides low-friction guidance within the shock body, reducing stick-slip that degrades small-bump sensitivity and ride refinement
• Extended bumper stop - an integrated end stop limits the shock's extension travel, protecting the shock and suspension components from over-extension under rapid droop conditions such as when the rear wheels drop into a ditch or the truck crests a rise at speed; the bumper stop absorbs the energy of reaching full extension, preventing a metallic impact at the end of travel
• Dust shield - a shield protects the piston rod and upper seal area from direct debris and water contact, supplementing the polyvinyl boot's protection in the heavily exposed undercarriage environment of a heavy-duty pickup truck
• Low-friction, self-lubricating seal - the rod seal maintains consistent, low-friction operation over its service life, contributing to small-bump responsiveness and preventing the premature oil weeping that results from a seal dried out by high friction and heat
• Double-welded loops at stress areas - the eyelet mounting loops are double-welded at the highest-stress points of the shock body, providing additional structural reinforcement at the fatigue locations that experience the most concentrated cyclical loading

Specifications

• Part Number: RS55047
• Series: RS5000X
• Position: Rear
• Fitment: 2005-2016 Ford F-350 Super Duty (4WD; SRW; Stock Height)
• Internal Design: Twin-tube, gas pressurized
• Body Diameter: 2.25 in. (enlarged twin-tube)
• Piston Rod Diameter: 16mm (nitro-carburized chrome)
• Piston: 35mm sintered iron, fluon-banded
• Collapsed Length: ~18.87 in.
• Extended Length: ~31.21 in.
• Shock Stroke: ~12.34 in.
• Upper Mount: Eyelet / Loop Bushing (rubber, black)
• Lower Mount: Eyelet / Loop Bushing (rubber, black)
• Extended Bumper Stop: Yes
• Compressed Bumper Stop: No
• Dust Shield: Yes
• Adjustable Valving: No
• Ride Height Application: Stock (0")
• Operating Temperature: -40°F to 248°F
• Quantity: 1 shock (single - order 2 for complete rear pair)
• Warranty: Limited Lifetime

Included Components

• 1x Rancho RS5000X rear shock absorber (RS55047)
• Polyvinyl protective boot (red)
• Mounting hardware (bushings, washers, nuts)

Product Description

The Rancho RS55047 is an RS5000X series rear shock absorber for the 2005-2016 Ford F-350 Super Duty in 4WD Single Rear Wheel configuration at stock ride height. It is the direct rear replacement for the factory shocks on this platform, sized for the OEM suspension geometry and engineered to improve on the performance of the factory shocks Ford installs on the F-350 - including the Rancho units installed on FX4 off-road package trucks, which are noted by owners as underperforming relative to the RS5000X.

The RS5000X's Cross Tuned technology and Progressive Engagement Valving are the key differentiators over conventional fixed-valving shocks: the progressive disc system allows early, controlled fluid flow at the beginning of each compression event, absorbing small and medium inputs gradually before transitioning to full damping resistance. On the F-350 - a platform carrying significant rear sprung weight and operating across a wide load range from empty to near GVW - this graduated damping response meaningfully improves ride quality over varied road conditions without sacrificing the stability and control needed under towing or payload. The enlarged 2.25-inch twin-tube body provides the fluid volume to sustain consistent performance across extended towing and work-use cycles.

Important fitment notes: The RS55047 is for 4WD SRW pickups only - it does not fit 2WD, DRW, or Chassis Cab configurations. It is a stock-height shock; lifted vehicles require a longer shock part number. For 2017-2024 F-350 Super Duty 4WD, the updated rear shock is RS55047A. The companion front shock for 2005-2016 at stock height is RS55042. Sold individually; two units are needed for a complete rear pair. Backed by Rancho's Limited Lifetime Warranty.