'18-'23 Mustang TH400 Swap Kit (Stage 1) | Next Gen Performance

Next Gen Performance Stage 1 TH400 Transmission Swap Package | 2018–2023 Mustang GT

At Next Gen Performance, we make transmission swaps simple. Traditionally, transmission conversions can be a nightmare—guesswork, wrong parts, and hours of fabrication. With years of hands-on installation experience in our in-house facility, we’ve developed complete bolt-in transmission swap packages that eliminate the hassle and uncertainty.

Our Stage 1 TH400 Package includes a TH400 transmission built by Proformance Racing Transmissions, rated for up to 850 horsepower. Each unit is hand-assembled, fully tested, and configured for high-performance street or drag applications.

 TH400 Transmission Features:

• Built by Proformance – proven durability and performance

• Rated to 850 HP

• Transbrake Valve Body – instant engagement for track use

• Direct Drum Modified for instant transbrake release

• Low-Drag Clutch Packs & End Play Clearance – for friction-free efficiency

 Complete Package Includes:

• Custom Torque Converter – spec’d to your exact setup

• Next Gen Billet SFI Flywheel (8-Bolt)

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

• Flexplate Bolts & ARP Converter Bolts

• Polyurethane Transmission Mount

• Derale Transmission Cooler with fittings and 20 ft. of cooler line

• Hurst/M&M Shifter – reliable, race-ready shifting

• Custom-Built PST Driveshaft with billet yoke

• Flexible Braided Locking Dipstick

• All Required Adapters & Hardware – everything you need for the install

⚙️ Required:

• 2018–2021 Mustangs require a Gen 1 or Gen 2 starter and block plate

? Optional Add-On:

AEM Electronics X-Series Temperature Gauge
Take your setup to the next level with AEM’s ultra-accurate digital temperature gauge. Designed for modern performance vehicles, it offers superior visibility and precision with features like:

• Auto-dimming display for optimal brightness

• 33% larger gauge face for better visibility

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

• Programmable LED warnings

• Peak/recall function via front buttons

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

• Compact 52mm housing and shallow depth for easy mounting

• Positive-lock connectors for a secure, vibration-resistant fit

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

Take the guesswork out of your swap—trust Next Gen Performance for a proven, plug-and-play solution built for serious power and reliability.