The squirrels are strong with this one. This ’91 YJ belongs to Doug Fowler and he’s left the four-cylinder under the hood along with the AX5 transmission. The NP231 got a TeraLow 4:1 kit which helps the squirrels turn those heavy 37-inch-tall Trepadors. A Dana 30 with an ARB Air Locker slings grit up front while a high-pinion Dana 44 with a Detroit gets it done out back. Both axles have 4.88 gears and a spring-over conversion provides the elevation.