• start here
  • logo jeep_jk
  • logo jeep_tj_lj
  • logo jeep_cj_yj
  • logo jeep_xj_zj

Advance Adapters TJ 2003-06, Rubicrawler W/ 42RLE Transmission & NP231

Be the first to review this product


Quick Overview


Advance Adapters TJ 2003-06, Rubicrawler W/ 42RLE Transmission & NP231

More Views


This new reduction unit replaces the stock 42RLE tailhousing with a 6 gear planetary reduction box featuring a 2.72 low range. This is a true bolt-in doubler that couples to the stock Jeep transfer case or an existing Atlas 2 speed.

The Jeep 42RLE transmission has a stock tailhousing that is approximately 7 inch long. The rear output shaft in this tailhousing is actually a spud shaft, that pulls out of the rear of the main transmission case and leaves the stock output shaft in place. The RubiCrawler has a custom input gear that couples to this transmission main shaft with no modifications to the transmission. This new input gear drives 6 planetary gears that gives the RubiCrawler the 2.72:1 reduction. The RubiCrawler housing is exactly the same length as the stock tailhousing and includes a new 23 spline output shaft that couples the rear of the RubiCrawler to the stock transfer case, leaving everything in the stock location. The RubiCrawler uses the oil feed from the transmission for lubrication and shares fluid with the transmission.

The RubiCrawler's shifting mechanism utilizes push/pull cable technology for a smooth and easy shift. The universal cable shifter is included with the purchase of your RubiCrawler. The universal shifter should be used if your vehicle is equiped with an Atlas transfer case.

We also offer a twin stick cable shifter for the Jeeps. These kits are designed to fit the stock TJ and JK consoles.

The Jeep TJ's twin stick shifter replaces the standard hard linkage. We have designed a twin stick shifter that comes through the stock console for a clean installation that operates the RubiCrawler and the stock NP231 transfer case.

The twin stick JK shifter also provides a twin stick shifter through the stock console. This kit retains the stock transfer case cable with the addition of the new RubiCrawler cable.

These shifters are a additional charge but are the best suited for most installations. Note, if your vehicle does not have a stock transfer case, The universal shifter should be used.

Ratio possibilities:

* Stock New Process 231/241 are a 2.72:1 and a 7.40:1
* Stock NP Rocktrac are a 2.72:1, 4.0:1 and a 10.88:1
* Atlas 2.0 are 2.0:1, 2.72:1 and a 5.44:1
* Atlas 3.0 are 2.72:1, 3.0:1 and a 8.16:1
* Atlas 3.8 are 2.72:1, 3.8:1 and a 10.44:1
* Atlas 4.3 are 2.72:1, 4.3:1 and a 11.70:1
* Atlas 5.0 are 2.72:1, 5.0:1 and a 13.60:1

Additional Information

Product Number ADVRUBI-TJ231A
Fits TJ 2003 - 2006, LJ 2004 - 2006

Product Tags

Use spaces to separate tags. Use single quotes (') for phrases.

Customer Service


WA 360-340-0282
CO 720-213-0114

Toll Free:




Customer Service Hours:
Monday - Friday 
9:00am - 6:00pm PST

Store Addresses: 
Northridge 4X4 - Washington
7976 Rubicon Trail Pl. NW
Silverdale, WA 98383 

Northridge4x4 - Colorado
4107 S Valley Dr
Longmont, CO 80504 

We accept the following methods of payment:

Buy now with PayPal




Free Shipping On All Orders Over $70, US Lower 48 States.
Only $9.99 on all items under $70


Support after the Sale
When you purchase from us you can be assured that we will be there when you need us. We pride ourselves on our friendly tech support and eagerness to help you out. So give us a call.


We Install What We Sell!
Northridge 4x4 is a full service off-road shop with a specialty in Jeeps. From installing fender flares to building the most extreme rockcrawler you can imagine, we do it all.

Gift Cards

Make Shopping Easy With A Northridge 4x4 Gift Card
Redeem online or at our retail store. Available in any amount from $10 to $1,000.
Buy Now Gift Card