93-99 AWD: You can very easily tell the gear set in these units. The pic below is of two 3rd and 4th gear shift forks. If your unit has the fork with the 3 rail holes (left), you have what we like to call the 93-99 gear set. This gear set will need our ‘94-99 EVO III 3rd and 4th Gear Install Kit’ in order for the EVO III double synchro 3rd and 4th gears to fit. The EVO III 1st gear, EVO III input shaft, and EVO III 5th gears will drop right in with no modifications needed.
Late 91-92 AWD: This is what we believe to be the best gear set you can get. In the pic above, the fork on the right with the 2 rail holes will be what you are looking for, but there is one more thing that needs to be checked to verify you have the right set. In the pic below you have two different gear teeth on the two center diff lower housings. You need the gear that is on the left side with the cut on the lower part of the tooth. If you have this trans, you are in luck! You can install the EVO III 1st, 3rd, 4th, 5th gears and input shaft with no install kits and no modifications. Those parts will pop right in!
89-Early 91 AWD: These have a different gear set than all the others and makes things a little more difficult when upgrading to the stronger gears. This unit will have the fork on the right with the 2 rail holes, but will have the center diff lower housing with the solid/smooth gear on the right. If you want to upgrade 3rd, or 4th you will need to replace the center diff lower housing to the one like the unit on the left in the pic, and replace the intermediate shaft with a later unit as well. Once all of this is done, it is almost identical to the Late 91-92 AWD trans in that all of the very cool and strong gears will pop right in with no kits or modification. The taller EVO III 5th gear will not work. The 5th/REV shift rail, fork, hub and slider, synchro rings, and case end cover will need to be replaced in order for it to run properly. We recommend in this case that you just buy a good rebuildable Late 91-92 core and rebuild it instead.