The Wrangler is unique in this series because you're dealing with three distinct transmission types across the JK and JL generations — a manual, a legacy automatic, and a modern ZF unit. Each has completely different failure modes, and misidentifying which unit is in the vehicle before diagnosis is a fast way to waste time. Let's get oriented. NSG370 6-speed manual (JK 2007–2018, 3.8L and 3.6L): The NSG370 is a Tremec-sourced unit and it's reasonably robust, but it has two consistent failure patterns. First: the input shaft bearing fails on high-mileage units, especially those used for rock crawling where low-speed high-torque operation is repeated frequently. You'll hear a growl or whine in all gears that changes with clutch engagement — bearing noise, not gear noise. Second: the synchronizer rings for 3rd and 4th wear prematurely on units that see frequent off-road use in low range with quick range changes. Symptom is grinding or resistance when shifting into 3rd, specifically when cold.
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ATSG Jeep 42RLE Transmission Rebuild Manual
Complete teardown, clearance specs, and clutch pack data for the 42RLE — the reference you need before opening one of these on the bench.
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