Chevrolet & GM Generation I-III+ Engines

to the

AMC Jeep Automatic Transmissions

This kit is discontinued. However, information regarding this conversion is retained below for the current time.

There have been a handful of good automatics in Jeeps over the years, including the AMC TH400, the AMC TF727, AMC TF904/909 and the AW4, and our customers have asked us to make them adaptable to the popular Chevrolet and GM Gen. III+ small-block engines.

Product & Features


The Adapter

This plate style adapter is precision laser cut and machined. Included are the adapter, flexplate, fastening hardware, and instruction guide. Precision CMM mapped and machined, offset dowel locators and fastening points assure total concentricity for long transmission life. The adapter is plated in black zinc for corrosion resistance and appearance.


Kit contains zinc plated adapter, flexplate, dowel locators, hardware and instructions.


Pricing and product information to the right is shown for informational purposes. We recommend calling in and ordering this kit so we can tailor it for your exact transmission. Otherwise, make your order and we will follow up with you via e-mail or phone to verify your technical details.


Applications & Compatibility


This adapter is compatible with the AMC / Jeep versions of these automatics:

  • AMC TH400
  • AMC 727
  • 904/999
  • AW4

The strength and features of the 727 make it a good match for the GM V8's, including this LS / Gen. III+ style engine.


The legendary TH400 in AMC form is ideal to handle GM power in an FSJ Jeep, typically 1974-1979.


The following Chevrolet & GM engines are compatible:

  • Gen. I-II Small Block V8
  • Gen. III+ GM V8 – .:*see notes on long crank version for 374-4:. (/knowledge/gm_crank_spacing.htm)
  • Chevrolet I6
  • Chevrolet Big Block V8*
  • Currently, only neutrally balanced engines are compatible. The Chevy 400 Small Block and Chevy V6 and other externally balanced GM engines are not yet compatible with these kits.

The automatic transmission in some Jeeps is typically relocated a small amount so that the engine can be installed in the most ideal location. However, some Jeeps, such as the FSJ with the 727 or TH400 might be able to keep the transmission in the factory location, especially if using our weld-in engine mounts, which give a little more installation freedom to the installer.

*Big Block V8's or other engines may not be appropriate for the strength of certain transmissions.

Related Products

Transmission Cooling

Transmission Cooling is critical to the life of all automatic transmissions. Conventional in the radiator tank coolers are simply not adequate for long life on a Jeep’s transmission. Here are the products we recommend for best performance and ease of installation.




Additional related products for these applications will vary greatly based on the engine selected. We have engine mounts, cooling products, transfer case adapters -- the full gamut of products you would need for your conversion. The links below and navigation to the left will guide you to the correct pieces.

Installation Requirements

The adapter is easily and quickly installed onto the engine and transmission, requiring no modifications to your engine or transmission flanges.


A new flexplate is included with your kit, specific to the engine you are installing. This conversion retains the factory GM starter.

Engines & Engine Mounting

GM Engine Mounts for JeepsIf converting to a V8 in conjunction with this upgrade, aftermarket engine mounts are available to ease its installation. Because of the broad spectrum of engines and vehicle combinations used with this adapter, it would be difficult to list them all here. Whatever your application, Novak likely has the perfect solution. From a 225 Buick V6 in a CJ2A to an LS3 in your JK, we’ve got you covered.

Novak's engine mounts, featuring excellent vibration dampening, superior strength, and impressive adjustability - adjustable even after the engine is installed. The design, strength, and affordability of our mounts are second to none.

Engine Placement Drivers Drop

Engine placement in these applications is an effort in compromise to find the best position overall as a package. Generally the engine will be about 1” or even more towards the right, (passengers’s side in the USA) away from the front differential in a Wrangler or similar application. This gives the best balance of weight (and more importantly clearance) for the driveshaft going to the front axle. Clearance is usually quite good in these applications; both the steering and front driveshaft push things towards the right. Fore and aft position will vary with the Jeep model and engine. Have a CJ5 and Gen I with a rear distributor? You’ll be better off a little forward for more rear driveshaft length and clearance for that HEI. If you are in a longer Jeep and using an LS engine with no distributor, you’ll have more fan clearance and better balance if you hold it to the rear. Usually for ground clearance tuck things up nicely for height to avoid damage to oil pans and other life giving parts in the Jeep. Common sense and taking a step back to look at things overall goes a long way.


Driveshaft length changes are often required. Most conversions to these transmissions will require that the rear driveshaft be modified to be shorter and front driveshaft longer.

Some installers, concerned about the expense of new or modified driveshafts, attempt to let the existing driveshafts dictate engine, transmission and transfer case location, often to the detriment of the project. Our recommendation is to prioritize the correct position of drivetrain components over saving a few dollars which is usually regretted in the long run with compromised positioning.

Driveshaft modifications and rebalancing can be affordable when performed by driveline, RV or tractor implement specialists. New driveshafts are an option, but not necessarily a requirement in regards to the actual successful conversion if your existing driveshafts are in good condition.

Jeeps that require extensive travel or specialty-built driveshafts have this option available through several fabricators across the nation. These are normally specified after placement of the new transmission and measured at vehicle ride height. As the rear driveline gets shorter, it is often advantageous to us a Double Cardan or “CV style” rear shaft with the correct geometry at the axle to minimize vibrations and possible binding.


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.

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