The factory rear upper control arms on the GMT800 are stamped sheet steel with rubber bushings — and the bushings are tired after 20+ years. Our Crawl RU2 swaps them for 1.5" OD, 5/16" wall DOM tubing — seamless, cold-drawn for tighter tolerances and higher strength — with Rock Jock Johnny Joints at both ends and adjustable length to correct pinion angle after a lift or leveling kit.
The Suburban gets used hard — full loads, full crews, and a lot of highway miles. After a couple decades of that, the rear suspension is showing its age, and the fixed-length arms leave you no way to re-align the rear axle after a lift. You feel it as a clunk under throttle, harshness over expansion joints, and a back end that floats when it's loaded. Switching to Core 4x4 brings the rear back where it should be — with stronger, more durable construction built in.
Quick Specs
Tubing: 1.5" OD, 5/16" wall DOM
Joints: Rock Jock Johnny Joints at both ends
Lift range: 0"–6" (6"+ fitment available)
Tier guide — Cruise (entry, factory-power daily — lifted or not) → Camp (mid, our most popular tier) → Crawl (top, this product). Crawl is built for extreme off-road, heavy towing, or high-HP builds. Johnny Joints at both ends handle that load better than bushings.
Hardware included — Every order ships with the bolts, nuts, washers, and the matching nut tab for the upper-arm frame-side mount. You don't need to reuse factory hardware or order anything extra. Replacement hardware is available as a standalone HWK SKU if you ever need more.
Pairing tip — Running a lift? These uppers are part of our 4-piece rear control arm set — step up to the 4-piece set to add the matching rear lowers and replace all four rear control arms in one job.
Suspension Type — Standard vs Autoride (Z55)
Choose Standard or Autoride (Z55) at checkout.
Autoride (Z55) trucks have factory rear air-leveling. The Autoride version of this part includes the ride-height sensor mounting tab on the passenger-side upper arm — required for Z55-equipped trucks.
Not sure which you have? Check the silver RPO sticker inside your glove box for the Z55 code.
Fitment: Chevy Suburban 1500 (2000-2006). Also fits Chevy Tahoe (00-06), Chevy Avalanche 1500 (02-06), GMC Yukon 1500 (00-06), GMC Yukon XL 1500 (00-06), GMC Yukon Denali (01-06), GMC Yukon XL Denali (01-06), Cadillac Escalade (02-06), Cadillac Escalade ESV (03-06), Cadillac Escalade EXT (02-06). 1500-series only — does NOT fit 2500-series HD trucks. Made in the USA. Lifetime warranty on construction.
Built With
Tubing: 1.5" OD, 5/16" wall DOM · Joints: Rock Jock Johnny Joints, both ends
| Make | Model | Submodel | Years |
|---|---|---|---|
| Chevrolet | Suburban 1500 | 2000 - 2006 |
Construction & Materials
Tubing: 1.5" OD, 5/16" wall DOM · Joints: Rock Jock Johnny Joints, both ends
| Brand | CORE 4X4 |
| Color | Black or Blue or Charcoal or Green or Light Green or Orange or Purple or Red or White or Yellow |
| Lift Size | 0" — 6" or 6"+ |
| Series | Crawl Series |
| Suspension Type | Standard or Autoride (Z55) |
| Mounting Style | Bolt-On |
Use the vehicle selector on our website to shop by your year, make, and model. On product pages, use the kit builder to select your color, series, lift height, and any add-on options, then add to cart. If you need help, call or email our team.
Standard orders typically ship within 1–3 business days of ordering. Custom color orders take approximately 5–10 business days. Because everything is built in-house, we can turn orders quickly even for custom specifications.
You can reach our team through the contact form on our website, or browse to the Contact Us page. Our team is available to answer pre-sale and technical questions before and after your purchase.
Reviews of Core 4x4
