Basics of a Marlin Crawler Dual Case Setup:
When Marlin founded Rock Crawling in 1994, he created what he called a "Dual Transfer Case"
. This term is actually inaccurate as there are not two transfer cases (nor are there four drivelines): There is still only one transfer case. Rather, he has duplicated the low range section (containing High-Netural-Low) of the transfer case.
"Don't Gear Down, Double Up!"
If you ever get a chance to go wheel'n with Marlin and sit with him at a campfire you'll be in for some amazing stories. He'll describe how Toyota pickups were outnumbered on the trails 30:1 by Jeeps, save for but a few Land Cruisers. How back in the 80s and early 90s very few people wheel'd Toyota pickups. How Jeeps owned & ran the show. And how it was common to be told to "get his Jap tin can off the trail".
As many know Marlin is famous for carrying a ton of recovery parts that he uses to help rescue broken rigs. But the reason why he began carrying so much is actually because he would go out for a weekend and never see another pickup for three days. He carried so much out of necessity. He'll even tell you it was out of fear. Forget about trying to find spare parts -- there weren't even other like vehicles on the trail.
The reason why Marlin was able to finally get recognition for Toyota pickups is due to the unique 4-housing design of the Toyota Gear Drive T/Case. The first housing contains the High-Netural-Low
(low range) components while housings 2-4 contain front and rear output components (2WD-4WD). A bit more is explained on this very old tech page of ours, https://www.marlincrawler.com/java/gearvschain.html
This design of the 1979-95 Toyota Gear Drive T/Case is highly unique and is unlike 99% of all mass produced 4WD truck transfer cases. This is not possible with any Jeep/GM/Ford/Chrysler/Nissan/Suzuki/etc t/case except for the older, unpopular, and almost 3 times more heavy NP203. This is why Marlin was able to transform the Toyota pickup into a break-out star: By extracting only the first housing, we can stack and combine High-N-Low sections, what Marlin calls a "Crawl Box"
, one after the other as many as desired like pancakes. Two? Three? Four? How about Ten?
The limiting factor is how much can be removed from your rear drive line -- and this is where the Toyota Hilux/4Runner and even more so these long wheelbase Tacoma's shine. The traditional Jeep has a very short wheelbase rendering this process either impossible or very difficult (requiring a very tall lift or repositioning the engine forward). The same applies for the classic FJ40 Land Cruiser (which used to be more common on the trail than Toyota pickups) and Suzuki Samurai. As such the Toyota pickup became extremely capable off-road and an overnight sensation all thanks to the Marlin Crawler. The rest as they say is history!