You are here


Base SKU: IGTC-151

We have gathered a few dozen core t/cases to bring back fully-built TacoBox Dual Case Units for a limited time!!

These TacoBox Units are built using adapters from our sister brand, Inchworm, and feature our Marlin Crawler 4.70:1 Low Range Gear Set, Marlin Crawler Double Roll bearing, Marlin Crawler 52% stronger HD Lower Cage Bearing, Marlin Crawler Dished Coupler, Marlin Crawler EcoSeal, Refurbished Toyota Shift Handles, Marlin Crawler Shift Knob, High Quality JIS Hardware, and everything needed to bolt into your rig! Hand-built in-house and ready for installation!

What is the TacoBox?

The TacoBox is a compact reduction unit based on the famous 29-year time-proven Marlin Crawler Dual Case 'Crawl Box' design and is inserted between your transmission and transfer case. To achieve this, front & rear adapters are used to convert the bolt patterns of both your transmission and transfer case. The front adapter is based on our 25% stronger 5/8" thick USA-made Billet Aluminum Adapter to mate a Marlin Crawler Reduction Housing behind your 23- or 26-spline automatic or manual transmission. The rear adapter is based on our 6th generation USA-made Billet Aluminum MC09 Adapter which bolts to your original transfer case, and is fully clockable in 5° increments. The result is the Marlin Crawler TacoBox™, a fully assembled Dual Case Unit ready to be installed into 1995 and newer Toyota and Lexus 4WD drive trains.

Marlin Crawler TacoBox undergoing installation

What does the TacoBox do?

The TacoBox has three shift positions that may be engaged from a stop:

  • High: High Range is 1.00:1 so shaft speed & torque enters and departs at the same rate and is used for normal City and Highway driving. The ECU and all associated systems such as cruise control, traction control, stability control, the full ensemble of Toyota Safety Sense, ABS, ATRC, and Crawl Control, function normally. City and Highway Fuel Economy is unaffected. The truck will feel and operate 100% like factory both on-road and off-road, 2WD or 4WD. The TacoBox is simply bypassed.

  • Neutral: Neutral is a fully neutral position and allows for such things as unloading the drivetrain to make it easier on the electronic t/case shift solenoid, if applicable. This is nice for many newer vehicles that do not have a Neutral t/case position.

  • Low: Low Range is our famous Marlin Crawler 4.70:1 ratio. When engaged, your truck instantly becomes 4.7-times more capable and will blow your mind at how much control the truck has and how easy it gets up and down obstacles.

The end result will look like this:

Engine > Transmission > TacoBox (4.70:1) > Transfer Case (2.57:1)
... thus transforming your 2-speed (1.00, 2.57:1) factory transfer case into a 4-speed (1.00, 2.57, 4.70, 12.08:1) TacoBox-equipped transfer case as follows:
Factory 2-speed T/Case

High Range (1.00:1)
Low Range (2.57:1)
TacoBox-equipped 4-speed T/Case

High Range (1.00:1) ← TacoBox in High, T/Case in High
Factory Low Range (2.57:1) ← TacoBox in High, T/Case in Low
TacoBox Single Low (4.70:1) ← TacoBox in Low, T/Case in High
TacoBox Dual Low (12.08:1) ← TacoBox in Low, T/Case in Low

In a 5-speed transmission example, the truck will now have 20 different forward gears and 4 reverse, making it a 24-speed truck!

Required modifications?

Required modifications include contracting with your local driveline shop to lengthen, shorten, and rebalance your front and rear shafts, lengthen the wires of your transfer case shift solenoid (if applicable), lengthen 6mm vacuum hose to shift base and solenoid (if applicable), and install a new shift handle into your interior by cutting a 2.5" hole in the center of your cab and modifying your center console. For automatic owners this usually involves modifying a cup holder, coin slot, or cubbyhole. For manual owners, a simple modification to your transmission boot is all that is needed.

Below is a collection of TacoBox Shift Handle Installations. Click an image for a larger view.

No factory crossmember modifications are required, however, modifications to under belly skid plates may be required depending on brand. The TacoBox includes provisions for an additional transfer case mount which is optional but when incorporated is a great addition to help lengthen the lifespan of your engine mounts! If desired, we offer a Heavy Duty 6cyl wide-style OEM Toyota mount here.


  • Increased Traction

  • Increased Torque

  • Increased Control

  • Increased Reaction Time

John Drives BigMike's Truck at 511:1
Discover how a Marlin Crawler
can make your truck unstoppable!
  • Less Bouncing

  • Less Breakage

  • Less Trail Abuse

  • Less Risk

→ Incredibly safe in downhill descents and drop-offs:

The TacoBox creates 4.7-times more Engine Compression resistance to movement providing 4.7-times more control, reaction time, and safety while also 4.7-times less required brake force when going down even the steepest drop-offs and ledges. Your truck can weigh up to nearly 5 times more than factory and yet will still descend down hills as safe as a factory truck. Going downhill is EXTREMELY safe with a TacoBox which provides UNPARALLELED driver control with no brakes required.

→ 2WD Low Range:

The TacoBox also provides a new Low Range that can be used independently of your factory transfer case, meaning you can now have Low Range even while in 2WD! This is very useful if you are backing a boat down a ramp, moving a trailer around your yard, or repositioning your truck in a tight camp ground and don't want to hassle engaging 4WD. Also, on the trail you can make sharp corners without having the issue of the front end binding with the rear end due to sharp corner radii. The new ways you may manipulate your truck is very useful with cutting brakes and performing other slow and controlled maneuvers on the trail.

→ Extra Drive train Mount (optional):

As mentioned, the TacoBox includes provisions for a 1979-1995 style Toyota 4cyl or 6cyl crossmember mount which may be used for additional drive train support! This is entirely optional but is a great feature that spreads the drivetrain torque helping prolong the lifespan of your engine mounts. For this, we offer a Heavy Duty 6cyl wide-style OEM Toyota mount here. Depending on application, exhaust modifications may be required. Click to view an example image of a HD OEM 6cyl mount installed.

→ Full List of Benefits:

In conclusion, here is a comprehensive list of benefits for both Automatic and Manual Transmission owners that you get from the Marlin Crawler TacoBox. Click the image for a larger view, and consider scrolling down to watch our many YouTube action videos below!

Proposition 65 Warning for California Consumers

WARNING: Products we sell can expose you to chemicals which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.p65warnings.ca.gov.

Marlin Crawler Dual Case Explained

Watch as BigMike explains how our Dual Transfer Case System works
at the 2017 FJ Summit in Ouray, Colorado (conversation begins at the 50-second mark)

How our TacoBox improves your truck's off-road capability

Short TacoBox Demonstration at Outer Limits

Automatic TacoBox Demonstration in 3rd Gear (91:1)

Rock Crawling Throttle Finesse with an Automatic

Using a Starter to verify Dual Case Load Reduction

Walking The Crawler up "The Wall" @ 580:1

Climbing "The Wall" at Poughkeepsie Gulch
with No Throttle in a 2016 Toyota Tacoma

Downhill with NO driver in a 2016 Toyota Tacoma

Dual Case Engine Compression Braking Demonstration

580:1 Triple Case TacoBox Demonstration