'18-'23 Mustang TH400 Swap Kit (Stage 4) | Next Gen Performance

Next Gen Performance Stage 4 TH400 Transmission Swap Package | 2018–2023 Mustang GT

At Next Gen Performance, we make transmission swaps simple. Traditional TH400 conversions can be a headache—guesswork, misordered parts, and countless hours of fabrication. With years of in-house installation experience, we’ve developed complete bolt-in TH400 swap packages that remove the uncertainty and deliver race-ready performance.

Our Stage 4 TH400 Package is designed for racers who demand extreme power. Featuring a TH400 built by Proformance Racing, this three-speed transmission is rated for 200+ HP, with a Pro Mod Sprag assembly engineered to handle up to 2000 HP (compared to the standard Borg Warner 34-element sprag rated to 850 HP).

 TH400 Transmission Features:

• Built by Proformance Racing – race-proven reliability

• Rated for 2000+ HP

• Pro Mod Sprag Assembly – extreme durability for high horsepower

• Reid Bell Roller Tail 2.48/1.48/1 3-Speed PRT Race Center Support

• 300M Main Shaft

• 36-Element Aluminum Direct Drum

• 1” 30-Spline Vasco Input with Steel Drum

• Billet Steel Forward Hub

• Race Pump with Split Circuit & Jet Fitting

• Billet Valve Body (available with clean neutral)

• Deep Transmission Pan

 Complete Package Includes:

• Custom Torque Converter – tailored to your application

• SFI-Certified Flywheel (8-Bolt)

• SFI-Certified Bellhousing – pre-installed and mated to the transmission

• Flexplate Bolts & ARP Converter Bolts

• Transmission Mount

• B&M Transmission Cooler with fittings and 23 ft. of cooler line

• Hurst Shifter – precision, race-ready shifting

• Custom-Built PST Driveshaft with billet yoke

• Flexible Braided Locking Dipstick

• All Required Adapters & Hardware – everything needed for installation

 Optional Add-On:

AEM Electronics X-Series Transmission Temperature Gauge
Monitor your transmission like a pro with AEM’s X-Series digital gauges, featuring:

• Auto-dimming display for perfect visibility

• 33% larger gauge face for easy readability

• User-selectable °F/°C display (100–300°F / 40–150°C)

• Programmable LED threshold warnings

• Peak/recall function via gauge face buttons

• AEMnet CANbus + 0–5V analog outputs for EMS or data logger

• Compact 52mm housing and slim depth for versatile mounting

• Positive-lock connectors for secure installation

Build Time: Approximately 2–3 weeks
Fits: 2018–2023 Mustang GT (Coyote)

Trust Next Gen Performance for a fully engineered TH400 swap package capable of handling extreme power with plug-and-play reliability.