I currently have a 78 CJ7 with 232 I6, T150 three speed and D20 transfer case. The plan is to replace the T150 with a CJ T18. Do I need to extend the D20 linkage since the T18 is longer than the T150? Also, where do I find gasket and gears to mate the T18 and D20? The T18 already has the adapter plate. I am a novice at this, so excuse my ignorance.
Yes you would have to extend the linkage. On T18/Dana 20's the linkage pipe was longer to keep the shifter inline with the tranny shifter. You can extend the pipe and linkage yourself with a little thinking and hardware store parts, find orignal T18/D20 linkage(good luck) or cut a hole your floorboards farther back to accommodate the shifter. I believe the T18 makes the D20 sit 3inches farther back than the T150.
The gasket for the T18/D20 is the same as the T150/D20. Call the usual 4x4 parts stores.
As for the gear, You will need the gear that was attached to the rear of the T18.
Don't forget that you will need the original T18 front driveshaft due to the incresed distance the D20 sits back. The rear will also have to be the T18 original or have yours cut down.
All very good info. I would just like to add that you can use the gear from the back of the T-150 on the T-18. That way you have the correct gear for the transfercase. They are both 6 spline so that is a non issue. Good luck. Nickmil.