Overdrive manuals and automatics. Pick your car to see the kits made for it. Universal parts that fit most cars are listed for everyone.
Swapping the original 3- or 4-speed manual, or 2- or 3-speed automatic, for a modern overdrive: a Tremec TKX 5-speed or T-56 Magnum 6-speed manual, or an automatic such as the 700R4, 4L60E, 4L80E, AOD, 4R70W or 6R80/10R80. Swap kits bundle the crossmember, bellhousing, clutch hydraulics and shifter.
Without overdrive a classic turns well over 3,000 rpm at 70 mph. It's loud, thirsty and hard on the engine. An overdrive gear drops cruising rpm by a quarter to a third, so you can keep a strong rear gear for acceleration and still cruise quietly. Vehicle-specific kits mean no cutting or fabricating for most popular cars.
Fit most cars
Pick your car above to narrow the list
Pick your car above to see 1 more kits made for specific cars.
Prices were checked Oct 11, 2026 at the store linked from each part, and they change often. Product photos are shown from that store or maker's page. Confirm fitment with the seller before you order. Amazon prices aren't shown here because they change constantly; the Amazon button shows the current price. Amazon and eBay links may earn us a commission.
30 makers and stores
Makes the TKX 5-speed and T-56 Magnum/Magnum-F 6-speed manual transmissions used in most classic-car overdrive swaps; sells them through dealers.
Illinois builder of Tremec swap packages and Tru-Street 700R4/4L60E/4L80E/4R70W automatics for pro-touring builds.
Covers: 1964–67 Chevelle, GTO & GM A-body, 1968–72 Chevelle, GTO & GM A-body
Tennessee Tremec dealer selling vehicle-specific 'Pro-Fit' TKX/Magnum swap kits, Hydramax hydraulic clutches and automatics.
Covers: 1967–69 First-gen Camaro & Firebird, 1967–72 C10 pickup, 1964½–70 Mustang
Sells vehicle-specific Tremec 'PerfectFit/EasyFit' conversion kits plus crossmembers, bellhousings, shifters and clutch hydraulics.
Covers: 1967–69 First-gen Camaro & Firebird, 1964½–70 Mustang, 1953–62 C1 Corvette, 1966–70 Mopar B-body (Charger, Road Runner, GTX, Coronet), 1968–72 Chevelle, GTO & GM A-body, 1970–81 Second-gen Camaro & Firebird and 4 more
Idaho shop selling Tremec auto-to-manual conversion packages (quote-built) and Stifflers transmission crossmembers, mainly for Fords.
Covers: 1964½–70 Mustang, 1967–72 F-100 pickup (Bumpside), 1979–93 Fox-body Mustang
Florida builder of performance 700R4, 4L60E and 4L80E automatics sold with matched torque converters in tiered builds.
Ohio builder of level-rated performance automatics (700R4, 4L60E, 4L80E, AOD, 4R70W) and torque converters.
Edelbrock Group brand making StreetFighter automatics, torque converters, shifters, flexplates and TV cables.
Holley brand making SFI-rated steel safety bellhousings for swapping manual transmissions behind LS, small-block and modular engines.
Holley brand making bellhousings, adapters and clutch forks for T-56/Magnum and other manual swaps.
Holley brand making shifters and bolt-in transmission crossmembers for Tremec and automatic overdrive swaps.
Covers: 1968–72 Chevelle, GTO & GM A-body, 1964–67 Chevelle, GTO & GM A-body
Sells complete manual-transmission install kits (bellhousing, flywheel, clutch, hydraulic release) and hydraulic clutch conversions.
Covers: 1967–69 First-gen Camaro & Firebird
Large US retailer carrying Tremec, Silver Sport, Lakewood, QuickTime and Ford Performance transmission swap packages.
Large US retailer carrying Tremec, TCI, Silver Sport and other transmission swap brands.
Classic British and Jaguar parts specialist selling bolt-in 5-speed gearbox conversions, including Tremec T-5 kits for E-Type and Vitesse/Mazda kits for MGB.
Covers: 1961–75 Jaguar E-Type
BMW drivetrain machine shop that rebuilds and upgrades Getrag 245 5-speeds used in BMW 2002 five-speed conversions.
Covers: 1968–76 BMW 2002
Maker of gear-type limited-slip differentials with patented zero-load torque transfer.
Covers: 1992–2000 Honda Civic (EG & EK), 1994–2001 Acura Integra (DC2), 1991–2005 Acura NSX, first generation
Retailer and fabricator of 1JZ/2JZ swap parts, engine management and drivetrain parts for Toyota, Lexus and Nissan drift platforms.
Covers: 1989–98 Nissan 240SX (S13 & S14), 1992–2000 Lexus SC300 & SC400, 1986–92 Toyota Supra Mk III (A70), 1993–98 Toyota Supra Mk IV (A80)
Alabama shop known for LS V8 swap kits and supporting parts for the second- and third-generation Mazda RX-7.
Covers: 1986–92 Mazda RX-7, second generation (FC), 1993–95 Mazda RX-7, third generation (FD)
Arizona NSX specialist selling engine management, forced induction, clutch and drivetrain parts for the first-generation NSX.
Covers: 1991–2005 Acura NSX, first generation
California maker of suspension, drivetrain and engine parts for vintage Datsun, Toyota and Mazda chassis.
Covers: 1984–87 Toyota Corolla AE86 (GT-S & SR5), 1985–89 Toyota MR2, first generation (AW11), 1970–78 Datsun 240Z, 260Z & 280Z (S30), 1968–73 Datsun 510, 1989–98 Nissan 240SX (S13 & S14)
Fremont, California shop selling race and OEM parts for the AE86 and AW11 MR2, with 4AGE and 3SGE BEAMS swap support.
Covers: 1984–87 Toyota Corolla AE86 (GT-S & SR5), 1985–89 Toyota MR2, first generation (AW11)
Toyota 4x4 drivetrain specialist making heavy-duty transmission, transfer-case and gear parts.
Covers: 1984–95 Toyota pickup & 4Runner, 1986–92 Toyota Supra Mk III (A70)
Paso Robles, California maker of engine and drivetrain conversion adapters, mounts and crossmembers for off-road vehicles including Toyota Land Cruisers.
Covers: 1960–84 Toyota Land Cruiser FJ40, 1980–90 Toyota Land Cruiser FJ60 & FJ62
Land Cruiser parts retailer selling engine and transmission conversion adapters for FJ-series trucks.
Covers: 1960–84 Toyota Land Cruiser FJ40, 1980–90 Toyota Land Cruiser FJ60 & FJ62
Maker of drivetrain and suspension conversion parts for Datsun, Nissan and other chassis.
Covers: 1970–78 Datsun 240Z, 260Z & 280Z (S30), 1968–73 Datsun 510
Colorado Miata specialist selling performance, turbo and drivetrain parts for every MX-5 generation.
Covers: 1990–2005 Mazda MX-5 Miata (NA & NB)
Specialist in LS V8 conversion kits and driveline upgrades for the Mazda MX-5 Miata.
Covers: 1990–2005 Mazda MX-5 Miata (NA & NB)
Maker of billet LS swap brackets, adapters and engine accessories.
Retailer of Honda and Acura performance parts including K-swap shifters and mounts.
Covers: 1992–2000 Honda Civic (EG & EK), 1994–2001 Acura Integra (DC2)
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