Already running one of QA1’s 4-Link Suspension Kits on your 1967–1970 Mustang? Upgrade your build with QA1’s fabricated 9” rear housing — engineered for seamless integration, improved strength, and simplified serviceability. This housing is purpose-built to withstand modern horsepower levels while maintaining precise suspension geometry and a clean, bolt-on installation. ENHANCE YOUR EXISTING QA1 4-LINK QA1’s 9” rear housing is designed to bolt directly to QA1 4-link systems, eliminating the need for custom fabrication. It features fully formed trailing arm brackets that reduce flex under hard acceleration and cornering, ensuring your suspension performs consistently under load. Whether you’re upgrading your street car or finishing a restomod project, this housing provides the perfect combination of strength, alignment precision, and OEM-level fit. EASY INSTALLATION & SERVICEABILITY QA1’s bolt-in design means no cutting or welding is required. Every detail - from the formed brackets to the integrated jack pad and fill/drain ports - is built to simplify installation and maintenance. If your Mustang already runs a QA1 4-link system, this housing bolts directly in for a precise, trouble-free upgrade.

Genuine QA1. Part number R904S.

Ships from US warehouse.

WARNING: California Proposition 65 — this product can expose you to chemicals known to the State of California to cause cancer or reproductive harm.