6-Inch Lift Kit with M1 Shocks for Ford Super Duty 4WD (2017–2022) — Part 55840
- Fits 2017–2022 Ford F-250 and F-350 Super Duty 4WD, XL through Limited — see the full fitment list
- Excludes gas engine, dually, manual shift transfer case, 3.5-inch rear axle tube, factory contact overload spring, and Tremor trucks
- Kit includes two M1 monotube shock pairs, front coils, radius arm kit and upgrade boxes, and a transfer case clocking kit
- 4.5-inch fabricated rear blocks with U-bolts; anti-axle-wrap design, no overloads
- Bolt-on installation with a downloadable installation guide available
The Trail Fortress check
Will it fit your truck?
✓ Fits
✕ Does not fit
- Gas engine models
- Dually models
- Manual shift transfer cases Does NOT fit models with 3.5" rear axle tube Does NOT fit models equipped with rear factory contact overload springs Does NOT work on models equipped with Tremor Factory Trim Package
About this kit
6-Inch Lift Kit with M1 Shocks, fitment-checked
Rough Country 55840 is a 6-inch lift kit for 2017–2022 Ford F-250 and F-350 Super Duty 4WD diesel models. Two pairs of M1 monotube shocks, front coils, radius arm drop and upgrade boxes, a transfer case clocking kit, and 4.5-inch fabricated rear blocks with U-bolts make up the package. Gas engine, dually, manual shift transfer case, and Tremor trucks are excluded.
This 6-inch lift kit for the 2017–2022 Ford F-250/F-350 Super Duty 4WD raises the front to sit level with the rear and opens up clearance for larger tires. Radius arm drop brackets reset caster so steering feel stays close to factory, while the fabricated anti-axle-wrap rear blocks handle the back of the truck. Confirm your truck before ordering: the kit rules out gas engines, dually axles, manual shift transfer cases, 3.5-inch rear axle tubes, factory contact overload springs, and the Tremor package. A downloadable Rough Country installation guide is available.
What’s in the box
Kit contents
- 1× 4.5 In Block U-Bolt Kit No Overloads 1563BOX4
- 1× Radius Arm Kit Box 512BOX1
- 1× Transfer Case Clocking Kit 55003
- 1× M1 MONOTUBE SHOCK PAIR 770754P
- 1× M1 MONOTUBE SHOCK PAIR 770805P
- 1× Univ. 3 4 X 4 1 X 1 2in U-Bolt Kit 7673
- 1× 6 Inch Coil Box 9296
- 1× Radius Arm Upgrade Box 53600991A
- 1× Radius Arm Upgrade Box 53600992A
Rough Country shares subassemblies across kits, so individual package labels can carry broader application ranges. The complete 55840 kit fits the vehicles shown in the fitment section above.
Specifications
Specs
| Brand | Rough Country |
| Part number | 55840 |
| UPC / GTIN | 00840269917974 |
| Lift height | 6 in |
| Shock package | M1 series |
| Shipping weight | 297 lb |
| Country of origin | US |
| Category | Suspension & Lift Kits › Lift Kits |
| Installation guide | Downloadable PDF |
Why buy here