6-Inch M1 Lift Kit for 2025–2026 Silverado 1500 4WD
- Fits 2025–2026 Chevy Silverado 1500 4WD in WT, LT, RST, LTZ, PPV, and High Country trims
- Front M1 loaded struts with a rear M1 monotube shock pair
- Does not fit LT Trail Boss, Custom Trail Boss, or ZR2 models
- Factory wheels will not work — 20-inch or larger with 4.5in backspacing required
- Cutting and drilling required; downloadable installation guide available
The Trail Fortress check
Will it fit your truck?
✓ Fits
✕ Does not fit
- LT Trail Boss or Custom Trail Boss models
- ZR2 models
- Factory wheels
Requires cutting and drilling. 20-inch or larger aftermarket wheels are required. Wheels must feature 4.5in backspacing to fit. Please test fit wheels prior to installation. Some aftermarket wheels may require 0.25" wheel spacer #1065. Fitment on this page is based on the manufacturer’s application data.
About this kit
6-Inch M1 Lift Kit, fitment-checked
The 2025–2026 Chevy Silverado 1500 4WD version of Rough Country's 6-inch kit, part 21640_A. M1 loaded struts handle the front, an M1 monotube pair handles the rear, and a mono-leaf rear kit box and front full skid plate are also in the kit. LT Trail Boss, Custom Trail Boss, and ZR2 trucks are not covered.
Ordering a 6-inch lift kit for the 2025–2026 Chevy Silverado 1500 4WD means committing to aftermarket wheels: factory wheels do not clear, and replacements must measure 20 inches or larger with 4.5in backspacing. Some wheel choices also need the 0.25 inch spacer, so test-fit before install day. The install itself involves cutting and drilling, and a downloadable installation guide is available to walk through it. Contents include heavy-duty cast knuckle boxes, a high-clearance crossmember, a front full skid plate, and the M1 strut and shock pairs. Shipping weight: 275 lb.
What’s in the box
Kit contents
- 1× 6in Kit Dr Knuckle Box 21730BOX5
- 1× 6in Kit Ps Knuckle Box 21730BOX6
- 1× 6in Kit Crossmember Box 217BOX11
- 1× Universal Kit Box 21630991
- 1× FR Full Skid 217BOX3
- 1× M1 Loaded Strut Pair 502067
- 1× M1 MONOTUBE SHOCK PAIR 770739P
Rough Country shares subassemblies across kits, so individual package labels can carry broader application ranges. The complete 21640_A kit fits the vehicles shown in the fitment section above.
Specifications
Specs
| Brand | Rough Country |
| Part number | 21640_A |
| UPC / GTIN | 00840269970757 |
| Lift height | 6 in |
| Shock package | M1 series |
| Shipping weight | 275 lb |
| Country of origin | US |
| Category | Suspension & Lift Kits › Lift Kits |
| Installation guide | Downloadable PDF |
Why buy here