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Trail Tough Rock Block:  Dual cases for a Samurai


Editor: Matt Verley

Astoria, OR – Which gears should I put in my transfer case? I wish there was an answer to that question!  I’ve owned over a dozen Samurais in the last 20 years, and had every available transfer case gearset in my transfer cases.  The Samurai tcase is a bit unique in the 4×4 world; high range isn’t a straight 1:1 pass through gear so when you install lower gears you enjoy a reduction in both high range and low range.  There are a number of different ratios available from different manufacturers, and each works well in a particular application.


Many years ago I took an extended trip to Death Valley with my Samurai.  I had 4.16:1 gears in that rig.  I found the high range was adequate for the dirt roads, but low range wasn’t low enough for the technical canyon sections.  A few years ago, Zukiworld went on a trip to Colorado.  On that trip, I had 6.5:1 gears in my transfer case.  I found myself constantly starting off in 5th gear in low range, then double clutching a shift into first-hi.  Then I’d run into an obstacle, and have to double clutch back into low range and grab 1st or 2nd gear.  Low range was too low for that trip.  A few years later, I ran the Rubicon with the same Samurai.  I had 4.9:1 gears in the transfer case at that time.  Though driveable, I found that I really needed lower gears as I repeatedly stalled the Samurai on the more difficult obstacles.   The 6.5:1 gears would have been nice, but as I needed to do some highway driving and “easy” trails on that same trip, that would have been too low.  So, what’s a Samurai owner to do?  Carry two transfer cases and swap them out when needed?  Or…dual cases!

There are a few of options for dual transfer cases for the Samurai; but I managed to get my hands on a used Trail Tough Rock Block so that’s what I’ll be putting in my rig.  I bought one of these new about 15 years ago for a Samurai that I no longer own, so I was familiar with its installation and operation.  Trail Tough no longer sells them, but they sold a good number of them over the years and there are a few of these floating around for sale used.  The rock block takes the place of the intermediate driveshaft between the transmission and transfer case, and it adds an additional 2:1 low range to your existing gears.  In my case, this gives me the normal high range, a 2:1 low range, a 4.9:1 low range, and a 9.8:1 low range.  This means I can drop the rock block in low for the easy two track trails, the tcase in low for the more challenging obstacles, and both cases in low for the really difficult technical stuff.

Installation is fairly easy, taking just a few hours and using basic tools.  Installation involves cutting the factory transmission crossmember, cutting a slot in the floor for the shifter, bolting the rock block in place, and bolting the new crossmember in place.  One Saturday, and I had an additional low range in my Sami.  Time to head back to the Rubicon!




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  1. Hello,
    great article, would love to source one for my Gypsy(samurai).
    could you guide me from where to source one. trail tough has stopped manufacturing.
    Is yours available now?

  2. Great video, thanks for sharing,

    I am also in a similar dilemma to install a 6.5:1 gear ratio, after watching your video, i am hooked on to the idea of dual transfer case. could you please advise where i can source the same or if your’s is available for sale?
    will be shipping it to India.

  3. where can i buy a rock block

  4. Gday,

    Great write up and videos,

    Were looking for a rock block to put into our suzuki sierra(samurai) here in perth Australia!

    Didnt know if you might know someone with kne for sale or if yours might be?

    Please let me know either way!


    • Hey, I’ve been to Perth! Pulled in there on the USS John C. Stennis in 2003 for liberty. Had a great time, too!
      I don’t know of any rock blocks currently for sale; but mine will be going up for sale sometime in the next year. I’m currently building a doubler that will replace the rock block, but won’t have it done for some time. I’ll let you know when mine does go up for sale…

  5. Great mod and easy install, thanks for sharing!

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