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|Performance Engineering Since 1988
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 per formance enthusiast looking for some bolt-in peace of mind.
Intended to be used in conjunction with our all new555-4050- Steeda HARDCORE S550 Mustang Differential Brackets.
You'll get an instant confirmation email with your part details and invoice. We source from a network of authorized suppliers across the country, so lead times vary by brand and part type — we'll send a tracking number the moment your parts move.
Made-to-order builds — carbon fiber bodywork, fabricated systems, custom finish work — run longer than off-the-shelf items because they're built per order. You'll get progress updates throughout the build.
Need a specific timeline on a part before you buy? Call 805-267-9762 or hit the chat — we'll check vendor stock direct and give you a straight answer.
Absolutely! Once your order ships, you'll get an email with a tracking link so you can follow its journey from our shop to your doorstep.
If your order ships via freight, you'll get a separate email with a direct link to the carrier's tracking page — easy and stress-free.
Things happen on the road — even to boxes. If your order arrives damaged, snap a few clear photos of the box and product and send them our way right away.
If your shipment is lost, just email or call us — we'll help track it down and guide you through the next steps to make it right.
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