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Np203 Transfer Case

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After a Glamis sand dune-running trip smoked the factory 700-R4 automatic transmission, Decker installed a Chevy Suburban-application TH400 automatic transmission and a fan-cooled, radiator-style B&M transmission cooler. He was fortunate to find a used NP203/205 Offroad Design Doubler transfer case setup online and that replaced the factory NP241 transfer case. In this photo you can also see the custom transfer case crossmember that's made from 1.750-inch-diameter, 0.120-inch-wall tubing. With the 2.48:1 TH400 First gear ratio, the 4.56 axle ratio, and the 2:1 or 4:1 low-range ratio the Jimmy has available crawl ratios of 22.6:1 and 45.2:1 respectively.