Part # 2051648 – Tacoma (1995-2004) Dual Case Adapter Kit

To open a printable PDF version of this instruction CLICK HERE
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Kit Includes:

  • (1) Coupler
  • (1) Adapter Plate w/Bearings installed
  • (1) Bearing Spacer
  • (1) Snap Ring
  • (11) Washer, Flat M10
  • (11) Washer, Lock M10
  • (12) Washer, Lock M8
  • (6) Bolt, M8-1.25 x 50
  • (2) Stud, M8-1.25 x 45



  • (5) Stud, M10-1.25 x 48
  • (2) Nut, M8-1.25
  • (5) Nut, Nylock, M10-1.25
  • (3) T-Case Keyway
  • (2) Dowel Pin, M10 x 14
  • (1) Gasket Kit
  • (2) Drain Plug w/Aluminum Washer
  • (1) Ultra Grey Silicone
  • (2) Dowel Pin M11x15

Tools Needed:

  • ⅜ Ratchet
  • 12mm, 14mm, 17mm, 30mm Sockets
  • 12mm, 14mm, 17mm, 30mm Wrenches
  • Air Wrench
  • Needle Nose Pliers
  • Hammer
  • 3/16 Diameter Pin Punch


  • Snap Ring Pliers
  • 6mm, 10mm Allen Wrenches
  • Gasket Scraper
  • Flat Blade Screwdriver
  • Adjustable Wrench
  • Blue LocTite
  • Axle Grease
  • 90W Gear Oil

Installation Notes:

    1. Read all instructions completely and carefully before you begin.

    2. Check to make sure the kit is complete and that no parts are missing. If anything is missing, please contact Trail-Gear at (559) 252-4950.

    3. Park vehicle on a clean, dry, at, level surface and block the tires so the vehicle can not roll in either direction.

Additional Items Needed:

    1. Core T-Case - Top Shift w/23spline Input.

    2. Replacement Cross-member.

    3. Second T-Case Mount.

NOTE: To build a dual transfer case crawler, you will need most of the parts that make up high/low section of a gear-driven Toyota transfer case. Below is a photo showing the factory parts that you will need from a stock transfer case.

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Installation Instructions:

1.Weld the provided key stock to the side of the shift fork as shown below. This prevents the front transfer case shifter from going side to side and only allows it to shift front and rear

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2. If your rear case has this hi-lo shift rail, follow step 3, otherwise, move on to step 5.

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3. Perform this step only after reviewing step 2. Cut 3/8” off of the flat side of the hi-lo shift rail
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4. After cutting, your shift rail should look like the bottom one in the image.
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5. Using a brush, apply axle grease to the base of the coupler.
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6. Slide the coupler bearing over the coupler.

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7. Grease the coupler bearing.

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8. Slide the 2.28 low speed gear over the coupler bearing.
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9. Slide the provided bearing spacer onto the coupler, above the low speed gear.
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10. Insert dowel pins into holes.

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11. Hold the bearing spacer with one finger and flip the assembly upside down. Slide the coupler (with spacer, bearing and low speed gear) into place on the dual adapter as shown below.
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12. Turn the adapter over so that the coupler is under the adapter. Apply the provided snap ring to the coupler.

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13. Turn the dual case adapter over so that the low speed gear previously installed is again facing up.
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14. Place the collar into the shift fork groove.

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15. Slide the high/low shift rail, fork, and collar onto coupler. Note the position of the shift rail going into the dual adapter.
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16. Fully seat the shift fork assembly onto the low speed gear. This may require turning the shift hub slightly.
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17. Apply grease to the dual case needle bearing.

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18. Install the counter shaft into the adapter plate needle bearing.
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19. Grease the pocket bearing from the original transfer case.
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20. Install the pocket bearing into the coupler.

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21. Slide the input gear into the coupler pocket bearing. Seat the input gear all the way down so that it meshes with the counter shaft gear.
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22. Place the gasket onto the face of the dual adapter as shown below.

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23. Install five of the new studs into the empty reduction housing.
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24. Place housing on the adapter.

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25. Start the nut as shown before fully mating the housing and adapter.
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26. Install two stock bolts in the passenger side of the dual adapter.
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27. Install the nuts and tighten.

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28. Slide the snap ring into place over the counter shaft bearing.
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29. Install the snap ring over the input gear bearing.

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30. Place the original detent ball into the hole on the passenger side of the dual adapter.
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31. Place the original detent spring into the hole on the passenger side of the dual adapter.
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32. Place a drop of LocTite® onto the detent ball plug and install into the adapter using a 6mm allen wrench.
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33. Install the drain plug and the gasket (provided with the kit) in to bottom of the dual adapter. Tighten using 10mm Allen wrench.
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34. Your crawl box is now completed.


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