FFP · AUTHORIZED DEALER
The leader in Ford performance · Over 35 years · MAP pricing
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AUTHORIZED DEALER
2015-2023 Ford Mustang – Steeda Threaded Differential Through Bolt Upgrade Kit
- Engineered and manufactured in Valdosta, Georgia
- CNC-machined billet construction where applicable
- Tested on Steeda's SCCA Majors race program
- Steeda authorized dealer — exact MAP pricing
Limited Lifetime Warranty
Backed by Steeda — FFP is an authorized Steeda dealer and warranty claims are honored direct.
Authorized Steeda Autosports dealer. MAP pricing — the same price as steeda.com. Expert install available at our Thousand Oaks, CA shop. Questions on fitment or setup? Chat with Senna or call our specialists.
The full breakdown.
Overview
Upgrade your S550 Mustang IRS differential hardware with Steeda’s all new through Threaded Differential Bolt Upgrade Kit. Through bolting the rear super 8.8″ differential to the IRS subframe on S550 Mustangs has become a popular modification due to premature bolt failure. Rather than permanently modifying your subframe by drilling out the bushings and differential housing, Steeda designed and machines in house a custom high strength hardened bolt that completely threads through the system. Post heat treatments the machined parts are nickel plated to prevent galling and provide superior corrosion protection. Using heat treated 4130 Chromoly steel, these custom bolts are as strong as a class 12.9 fastener and have been proven to last on some of the quickest and fastest S550 Mustangs out there, including Steeda’s Silver Bullet.
Steeda’s S550 Mustang THRU Threaded Differential Bolt Upgrade Kit is a must for all performance enthusiast looking for some bolt-in peace of mind.
Intended to be used in conjunction with our all new 555-4050 – Steeda HARDCORE S550 Mustang Differential Brackets.
Key Benefits
Specifications
Fitment
2015-2023 Ford Mustang Mach 1/Bullitt/GT/EcoBoost/V6.
Steeda has been engineering and manufacturing Ford performance parts in-house in Valdosta, Georgia for over 35 years — proven on their own SCCA Majors race team and trusted by enthusiasts who live and breathe Ford. CNC-machined billet construction, proprietary CAD-driven suspension geometry, and a relentless focus on the platforms they specialize in.
QS-9000 & ISO 9001 manufacturing · Limited lifetime warranty on Steeda-manufactured parts · Made in the USA
FFP fits Steeda parts every week in Thousand Oaks.
— Why we stock Steeda
OE-style engineering, in-house manufacturing, race-proven on Steeda's own SCCA program.
Steeda has been engineering Mustang — and now Explorer, Focus, F-150, and Maverick — parts in Valdosta, Georgia since 1988. CNC-machined billet, proprietary CAD-driven suspension geometry, and a factory SCCA Majors road-racing team that runs their own parts on the track every weekend. When you bolt a Steeda part onto your car, it's the same part Steeda's own race cars run.
We carry Steeda because the fitment is right the first time, the warranty is real (lifetime on Steeda-manufactured parts), and the install instructions don't leave you guessing. Drop the car at our Thousand Oaks shop and our techs handle the fit-up — or order with confidence and run it yourself.
Authority: Charles Siritho · McLaren Artura Trophy owner · Spotter for Branden Sorensen FD Pro (E46 LS+Whipple, 6th at Long Beach R1 2026) · 10+ yrs Mustang & Corvette specialist
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Shop the full Steeda catalog at FFP.
The leader in Ford performance — suspension, intakes, exhaust, brakes, wheels, and more — for Mustang, Bronco, Bronco Sport, Explorer, F-150, and Maverick. Enthusiast-driven, race-tested. MAP pricing always. Expert installation in Thousand Oaks, CA.
