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Adapting the
Jeep 4.0L I6 Engine
to the
Chevrolet / GM Hydramatic Transmissions

Widely considered to be the best automatic transmissions in the world, General Motors HydraMatics make for outstanding upgrades into Jeep powertrains. This adapter assembly brings the Jeep / Mopar 4.0L engines together with Chevrolet style automatic transmissions, including the TH350, TH400, TH700R4, 4L60, and Early 4L60-E* transmissions.

Adapting Jeep 4.0L engines to 700R4, TH350, TH400
Kit 437AMC-5, adapting the Jeep 4.0L engines to GM HydraMatic transmissions
Part #: 437AMC-5
Weight: 14.39
Price: $610.82
Includes the adapter, flexplate, crank reinforcement ring, shield plate, access port plate, crank position sensor (CPS), CPS bracket, torque converter spacer, fastening hardware and instructions.

The Adapter Kit
This plate style adapter is precision laser cut and machined. Included are the crank spacer, flexplate, flexplate spacers, flexplate reinforcement ring, crank position sensor, CPS mouting bracket and fastening hardware. Additionally, we include a shield plate with a convenient access port for your torque converter bolts.

Precision CMM mapped and machined dowel locators and fastening points assure total concentricity for long transmission and torque converter life.

The adapter is plated in black zinc for corrosion resistance and appearance.

Transmission Versions
The Chevrolet style HydraMatic transmissions, including the:

*The electronically controlled Early 4L60E will require a transmission control unit, which - while effective - are somewhat expensive. The installer may consider the conventionally controlled 700R4.

The Later Style 4L60-E (removeable bellhousing, hex rear bolt pattern) are not candidates for this conversion.


All Mopar style 4.0L engines from 1991-2004 are compatible with this conversion. For AMC 258, 304, 360 & 401 adaptations, see this page.

Renix era 4.0L engines (1987-1990) and SFI 4.0L engines (2005-2006) are not compatible with the Crankshaft Position Sensor (CPS) included in this kit. You may choose our standard 258 / 4.0L adapter kit and use a separate, harmonic balancer style Crankshaft Position Sensor relocation kit.

The adapter is easily and quickly installed onto the engine and transmission.

Installation of the included CPS assembly will require that a 1/2" hole be drilled into the bellhousing of your HydraMatic transmission. This is a simple and rapid process and will not affect the integrity of the transmission case. A drill jig and instructions are included.

This conversion also requires the use of a 1980’s era, CJ 258 I6 starter in lieu of the 4.0L starter. You can exchange your starter towards a new or remanufactured CJ starter at your local parts house.

Jeep 4.0L crank position sensor for Hydramatic conversions
Sensor, switch, digital speed, threaded barrel style
Part #: S-340CPS
Weight: 0.03
Price: $54.47

Crank Position Sensor
The included Crank Position Sensor is an industrial grade unit built for great longevity. But, instead of mounting this CPS obscured inside the transmission bellhousing, it installs externally, making it field-replacable. Extra sensors are inexpensive and compact enough to carry in any toolbox.

Your Torque Converter
The grand majority of GM torque converters have the standard size three-bolt pattern that is ~10-5/8" on diameter. However, some factory or aftermarket heavy-duty TH400 torque converters (as seen in RV and heavier truck applications) may use a larger bolt pattern diameter, which is not compatible with our particular flexplate that is included with this kit. You may wish to exchange this converter towards one with the standard diameter bolt pattern. The converter can be rated at any duty or stall you wish.

Engines & Engine Mounting
In essentially all installations, these factory Jeep engines will remain in their original locations.

Transmission Location & Transmission Mounting
When replacing the AX15 transmission with the TH350, driveshaft lengths can remain the same. The TH400 and 700R4 / Early 4L60E conversions are longer and will require length modifications to your driveshafts. Crossmember mounting for these transmissions is generally simple, and discussed in greater detail for these transmissions in our Transmission to Transfer Case Adapters section.

Use of factory axles is completely acceptable with this conversion. Axle upgrades are not necessary, but they may be chosen for reasons external to this transmission upgrade.