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Alloy USA Differential Permanent Lock Kit for Front Dana 30 (87-95 Jeep Wrangler YJ)

Item J11886
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      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Differential Permanent Lock Kit with Front 30
      • Works with 1987 - 1995 YJ Wranglers


      Specs. The Differential Perma-Lock Kit from Alloy USA is a permanent replacement. It's just what you need when your failure prone OE vacuum disconnect system is not working as well as it should.

      Construction. This kit permanently engages the central axle disconnect, also known as the CAD, and combines both axles in the front. When it's installed, the axles will automatically engage when the transfer case is put into 4-wheel drive.

      Application. This differential kit works with 1987 - 1995 Wrangler YJ models.

      Fitment: 1987 1988 1989 1990 1991 1992 1993 1994 1995 Details

      MPN# 451100

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (12)

      Write a Review

      Ratings Summary

      4.2 out of 5 overall rating from 12 customers

      • June 04, 2019

        4 1989 Wrangler - EugeneC

        Works if you can do modifications

        It works well if you can do your own modifications, you will most likely need to file it in a few spots and make things fit, this is typical with a Jeep though so you should be able to do it fairly easy, only took about 45 minutes to install and you don't notice it in 2 wheel drive on your transfer case, no wheel hop but locks it up when needed.

        Helpful (2)
      • October 07, 2018

        5 1993 Wrangler - RobertH

        CAD delete

        Easy install and so far has worked great keeping the two piece shaft locked together.

        Helpful (9)
      • August 19, 2018

        3 1995 Wrangler - DarrolP

        1995 jeep Wrangler

        I want to install this product in my jeep but one of the other reviews said you can't flat tow anymore. I need to know if I can still tow my jeep after I install this part? As I'm only one person and can't drive both my truck and jeep.

        Helpful (20)
      • July 18, 2018

        4 1995 Wrangler - MichaelJ

        95 wrangler

        It’s works easy install, but your 4x4 light will always be on,

        Helpful (14)
      • April 03, 2018

        2 1990 Wrangler - TroyR

        Needs work

        The rod wouldn’t fit through the fork(had to drill it out) Once the fork was in the casting it wouldn’t move to place it in the right spot. Spent another half hour grinding on the fork to make it work. But it works so I guess it’s ok.

        Helpful (13)
      • January 16, 2018

        5 1994 Wrangler - PeterG

        Easy and inexpensive.

        This is an easy and inexpensive fix to a known problem.

        Helpful (10)
      • January 15, 2018

        4 1991 Wrangler - likemyjeep

        had it installed

        unfortunately the weather turned cold just as i got it, since i have to work outside i had a mechanic install it. he said it could have been easier but not too bad. took him a little over an hour with a lift and good tools. just picked it up and the 4x4 light is on but it doesn't drive like it is in 4x4. got home and on dirt and tried it out and seemed to work fine. guess that maybe something inside makes it think is is always in 4x4. but otherwise so far so good. just have to remember i can't flat tow anymore.

        Helpful (15)
      • November 24, 2017

        4 1995 Wrangler - DanV

        Decent quality, missing pieces

        When mine arrived it was missing the small bag of hardware, e clips, washers, connectors etc. took about 9 days of back and forth with customer service but they sent out the hardware- got it installed and works as advertised, had to look up installation instructions online, none provided. Took about an hour including me breaking a bolt.

        Helpful (10)
      • November 07, 2017

        5 1993 Wrangler - BillyS

        Great Product

        Great product easy to install. Love to do business with Extreme Terrain

        Helpful (10)
      • June 22, 2017

        5 1988 Wrangler - PaulR

        Alloy USA permant lock

        Easy to install and works great I used it immediately after installation

        Helpful (10)

      Questions & Answers (11 answers)

      5 Top Rated Questions

      After installing can you still flat tow your Jeep

      • With the lock engaged, you would greatly reduce your YJs flat towing ability due to the way it will lock the front axles. You will want this disengaged so that the wheels can spin freely.

      Helpful (4)

      After this is installed both front axles work at the same time without none of them disconnecting and three tires are working at the same time? The two in front and one or the other in the rear.

      • This will make the front axles automatically engage when the Jeep is put into 4WD, it would not change the function of the rear axles. 

      Helpful (1)

      Does this kit have any effect on handling on-road in 2wd?

      • The Alloy USA Differential Permanent Lock Kit for Front Dana 30 will have minimal effect on road handling in 2wd. In 4WD this will get rid of the vacuum disconnect that is prone to failure.

      Helpful (1)

      The web site has 2 answers for the flat towing question, 1 says you must disengage the front axle, the other says flat towing is fine with it engaged. Can you clarify? Thank you.

      • With the lock engaged, you would greatly reduce your YJs flat towing ability due to the way it will lock the front axles. You will want this disengaged so that the wheels can spin freely.

      Helpful (0)

      I realize the wheels will turn the same rate when flat towed, but will this create backlash to transfer case? In other words, can I flat tow without destroying my drivetrain?

      • This kit will lock the front axles to the carrier, however if the transfer case is in 2wd or neutral, then this will not cause any additional wear on the transfer case.

      Helpful (0)
      Post Your Question
      6 More Questions
      Can I use the same shifting fork? 1 answer
      Does this come with the shift fork? 1 answer
      will this effect anything when flat towing? 1 answer
      Will it make me have wheel hop in 2wd? 1 answer
      Does it engage and disengage as needed or is it permanently in 4wd after installation? I am new at all of this jeep stuff. 1 answer
      I drive a 89 xj Cherokee with the cad style Dana 30. I assume it used the same axle as the wrangler so im Just wondering if this will work on that axle also? 1 answer

      Installation & What's in the Box

      What's in the Box

      • (1) Cover
      • (1) Gasket
      • (1) Hardware

      Tech Specs

      Will It Fit My Wrangler

      • YJ Wrangler 2 Door - 87, 88, 89, 90, 91, 92, 93, 94, 95

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