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Gear Reduction Unit

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Also lengthening the drivetrain is a 4-to-1 Crawler (arrow), an add-on gear-reduction unit that fits between the tranny and the transfer case without the need for adapters. It uses NP241-style planetary gears, and thanks to aftermarket gear availability you can choose a ratio of 2.72:1 (which is what we used), 3.50:1, or 4.0:1. With the NV4500 and 5.89 axles, the crawl ratio is 265:1. Overall length of the crawler box is 7 1/4 inches, negating its use with even a CJ-7 (94-inch wheelbase) unless you get really creative with a short trans and a V-6 moved far forward. The crawler-box shifter is cable-actuated so its linkage is no problem; however, the crawler moves the transfer case rearward, so fabricating longer linkage is required.