ReadyLIFT 1.75" Leveling Kit with UCAs | 2019–2025 GMC Sierra AT4 & Chevy Silverado Trail Boss
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Before ordering, verify your vehicle details, current setup, and SKU with OFAS fitment support so your upgrade matches your build.
Shipping & Delivery
Free shipping is available within the lower 48 U.S. states. Large or heavy items may ship by freight, and delivery timing can vary by warehouse, carrier, and product availability.
Fitment, Shipping & Product Support
ReadyLIFT 1.75" Leveling Kit with UCAs | 2019–2025 GMC Sierra AT4 & Chevy Silverado Trail Boss
Is This for You?
You're running a 2019–2025 GMC Sierra 1500 AT4 or Chevy Silverado 1500 Trail Boss — trucks that come from the factory with a 2" front lift and longer strut assemblies — and every generic leveling kit on the market either binds the factory ball joint or contacts the lower strut and CV axle assembly. You need a leveling kit engineered specifically for the AT4 and Trail Boss platform that works with the factory suspension lift, not against it. The ReadyLIFT 66-3921 delivers 1.75" of additional front leveling lift with CNC-machined billet aluminum strut spacers and DOM steel UCAs with corrected geometry — purpose-built for this platform.
The Result
CNC-machined aircraft-grade billet aluminum top and bottom mount strut spacers deliver 1.75" of front leveling lift that works in concert with the factory 2" lift — providing the required amount of lift without conflicting with factory strut geometry or clearances. Heavy-duty DOM tube steel upper control arms with corrected ball joint cup angles, 1-ton heavy-duty replaceable ball joints, and ReadyLIFT TCT (Terrain Control Technology) maintenance-free pivot bushings with side-biter washers restore proper suspension geometry and improve alignment retention at the new ride height. Trail Boss trucks clear a 295/65R20 on a 20x9 0-offset wheel; AT4 trucks clear a 275/60R20 on the same spec — fender opening design differs between the two models.
Verified Fitment (OFAS Standard)
✅ Fits: 2019–2025 GMC Sierra 1500 AT4
✅ Fits: 2019–2025 Chevrolet Silverado 1500 Trail Boss
❌ Does NOT fit: GMC Sierra 1500 AT4X
❌ Does NOT fit: Chevrolet Silverado 1500 ZR2
❌ Note: AT4 and Trail Boss have different front fender opening designs — maximum tire size differs between the two models; test fit before finalizing tire selection
| Spec | Detail |
|---|---|
| Lift Height Added | 1.75" (additional, works with factory 2" lift) |
| Front Strut Spacers | CNC-machined aircraft-grade billet aluminum top and bottom mount strut spacers |
| UCAs | DOM tube steel, corrected ball joint cup angles, 1-ton HD replaceable ball joints, TCT maintenance-free pivot bushings with side-biter washers |
| SKU | 66-3921 |
| Manufacturer | ReadyLIFT |
Wheel & Tire Fitment
| Application | Max Tire | Wheel | Notes |
|---|---|---|---|
| Chevy Silverado Trail Boss | 295/65R20 | 20x9 0 offset | No trimming required |
| Chevy Silverado Trail Boss (factory wheels) | 285/75R18 | Factory 18" wheels | Wheel spacers required |
| GMC Sierra AT4 | 275/60R20 | 20x9 0 offset | No trimming required |
AT4 and Trail Boss have different front fender opening designs — do not assume the same tire size fits both models. ReadyLIFT wheel and tire fitment recommendations are based on Wheel Pros wheels and Nitto tires. Actual dimensions vary meaningfully by manufacturer — overall diameter, tread width, aspect ratio, and sidewall construction will differ. Every tire and wheel combination must be test fit prior to final installation. Upgrading to heavier 10-ply (Load Range E) all-terrain or mud-terrain tires will noticeably increase suspension stiffness and alter ride harshness compared to factory 6-ply (Load Range C) tires. Consult your local installer for application-specific guidance.
Installation & Engineering Notes
This is a bolt-on leveling kit requiring no cutting or welding. UCA hardware must be torqued to specification at ride height. A professional 4-wheel alignment is mandatory post-installation to verify torque specs and lock in corrected geometry. Lifting your vehicle raises its center of gravity; exercise appropriate caution on- and off-road. All Advanced Driver Assistance Systems (ADAS) including GM Safety Alert Seat, Lane Keep Assist, Forward Collision Alert, and automatic headlight leveling must be checked and recalibrated after installation.
Engineering Question: Is your truck a GMC Sierra AT4 or Chevy Silverado Trail Boss, and what is your model year? AT4 and Trail Boss have different fender opening sizes that affect maximum tire fitment — confirm your specific trim before selecting your tire and wheel combination.