Th400 Speedometer Gear Calculator, ATI now has an answer for this market and offers three variations of a 2-speed Turbo 400! OEM cased units are rated to 1800 HP and not intended for heavy weight cars. ATI SuperCase recommended over 2000 HP! Can be made PG lenghth at no additonal charge. The versatile TH400 was used in a variety of applications, including 1982 to 1990 GMC/Chevrolet 3/4 and 1 ton pickups equipped with the 6. Transmission Specialties offers many different levels of TH400 transmissions and can be tailored to your specific application with a wide range of premium options, including a TSI SFI-approved two-piece cast aluminum case or an OEM-inspected factory case. Find a large selection of reliable TH400 transmissions for your 2WD or 4WD vehicle at Summit Racing. The Turbo-Hydramatic or Turbo Hydra-Matic (THM) series was developed to replace both the original Hydra-Matic models and the Buick Dynaflow. As power and torque figures climb, the factory parts start to show their weaknesses: broken sprags, input shaft failures, and hydraulic inefficiencies that cause parts failure. It was introduced for the 1965 model year and made its debut in Cadillacs, and is respected for its durability and adaptability. Oct 1, 2025 ยท The TH400 (Turbo Hydramatic 400) is a widely popular unit in drag race, off-road, and street builds. Home Transmissions TH400 Transmissions TH400 Transmissions Sort By: FTI Performance TH400 Racing Transmission - Sportsman Transbrake - Level 4 $2,549. tok8z2uk, l6b, p7zt0p, zuk, wc6eri2, hbm, bhg, av8r, mx9mv, gvko,