6-Inch Lift Kit with M1 Shocks for Ford Super Duty 4WD (2017–2022) — Part 55640
- Fits 2017–2022 Ford F-250 Super Duty 4WD, XL through Limited — check every exclusion below before ordering
- Does not fit dually trucks, gas engines, manual-shift transfer cases, 4-inch rear axle tubes, factory contact overload springs, or Tremor-package trucks; F-350
- Kit includes 6-inch front coils, radius arm kit plus upgrade brackets, transfer case clocking kit, and 4.5-inch rear blocks with U-bolts
- Two pairs of M1 monotube shocks cover front and rear damping
- Bolt-on installation; downloadable installation guide available
The Trail Fortress check
Will it fit your truck?
✓ Fits
✕ Does not fit
- Dually models
- Manual shift transfer cases Does NOT fit gas engine models
- Models with 4" 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
Does NOT F-350 models. Fitment on this page is based on the manufacturer’s application data.
About this kit
6-Inch Lift Kit with M1 Shocks, fitment-checked
Rough Country 55640 is a 6-inch lift kit for 2017–2022 Ford Super Duty 4WD trucks, built around front coils, radius arm drop and upgrade brackets, fabricated 4.5-inch rear blocks with U-bolts, a transfer case clocking kit, and two pairs of M1 monotube shocks. The exclusion list rules out dually trucks, gas engines, manual-shift transfer cases, 4-inch rear axle tubes, factory contact overload springs, Tremor-equipped trucks, and F-350 models — verify your configuration first.
This 6-inch lift kit for the 2017–2022 Ford Super Duty 4WD covers XL, XLT, Lariat, King Ranch, Platinum, and Limited trims listed in the fitment section. Front coils raise ride height while the radius arm drop brackets reset caster to keep steering behavior close to stock, and the fabricated rear blocks are shaped to resist axle wrap. Two pairs of M1 monotube shocks handle damping front and rear. Read the exclusion list closely — it covers dually, gas-engine, manual-shift transfer case, and Tremor trucks — then work from the downloadable Rough Country installation guide. Shipping weight: 271.0 lb.
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× 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 55640 kit fits the vehicles shown in the fitment section above.
Specifications
Specs
| Brand | Rough Country |
| Part number | 55640 |
| UPC / GTIN | 00840269917950 |
| Lift height | 6 in |
| Shock package | M1 series |
| Shipping weight | 271 lb |
| Country of origin | US |
| Category | Suspension & Lift Kits › Lift Kits |
| Installation guide | Downloadable PDF |
Why buy here