Adapting the

AMC 2.5L (150cid) Engine


GM Transmissions

Adapting AMC 2.5L engine to GM Transmissions

This guide will show you how to replace your light-duty AX5 as found behind the AMC 2.5L I4 engine with something substantial, like the SM420 or SM465 transmissions. This is a more advanced swap, but the handy installer will be able to do good work.

Parts Required

The installer will need to source the following parts. These are suggestions only and do not constitute a guarantee of fitness or applicability:

  • Bellhousing, Chevy S10 Blazer. GM #15679692. This is the bellhousing that was used with the 2.8L, 60 degree V6 engine from 1985-1989. GM no longer manufactures this bellhousing, but salvage sources are an option
  • Plate, cover, bellhousing lower, GM #15602627
  • Bearing, throwout, BCA #614037 is one possibility, but the best option is to use Novak's adjustable release bearing, #TB1 available below
  • Arm, clutch release, GM #15704443
  • Cylinder, hydraulic slave clutch release. Try #SC103471 or Centric #13862003
  • Starter motor, gear drive style. Consider the Mean Green #3212

Novak can provide the following specialty parts to assist in completion of this conversion:

  • Pressure plate, & Disc, 9-1/8" diameter x 10, 1-1/8" splines available below
  • Adjustable release bearing, Novak #TB1
  • Bracket, mounting, crank position sensor
  • Pivot ball, specially modified for adjustable height
  • Adjustable pivot bolt, 10mm & lock nut
  • Adapter, hydraulic clutch release line (below)


CPS Provision

you may use your existing CPS (Crank Position Sensor). you will need to drill or otherwise machine your bellhousing to accept this sensor. The Novak CPS bracket and your CPS will offer you a good template for doing this modification. See Related Products, below.

Suggested Transmissions

The ultra-low geared SM420 or SM465 transmissions will add fantastic off-road and crawling abilities to your Jeep powertrain. These are the most often requested transmissions and will offer the best overall performance.

The SM465 is more difficult to install in that it requires that the bellhousing bore be machined to precisely accommodate the 5-1/8" retainer locator. Also, use of the suggested slave cylinder will require that one rib be machined off the SM465 on the driver's side. As such, the SM420 is usually an easier choice for installation, though a more difficult transmission to find.


We recommend that you run a 33 inch or greater tire or change your axle gearing to compensate for the loss of your overdrive gear. See our gearing page for more about this.

Transfer Case Shifter

This transmission conversion will work best in YJ Jeeps with our #SK2X transfer case shifter kit, and for TJ Jeeps, our #SK2XC cable shifter kit. Factory shifters could be modified, but these are kind of a mess to work with.

Transmission Shifter


Use of the OEM style transmission shifter for the transmission is easily done. The installer may opt to bend the stick to fit the particular Jeep application. The transmission shifter sits further ahead in the Jeep than the AX5 and will need to be modified accordingly.


Note that you will be able to shorten your drivetrain length and lengthen your YJ or TJ rear driveshaft for better angularity and less strain and vibration. The front driveshaft will be lengthened a corresponding amount.

Engines & Engine Mounting

your engine will remain in its factory location, using factory style or aftermarket mounts.

Related Products

Hydraulic release adapter fitting
Hydraulic release adapter for Jeeps
Hydraulic release master kit for Jeeps
Adjustable clutch release throwout bearing

Also See