 On many trails both in Utah and other places, the gearing reduction of low range is desired to keep the vehicle under control and to avoid riding the brakes. However, when a sharp turn must be made on a slickrock surface, it's like engaging 4wd on dry pavement. Lots of binding, jerking, and tire barking ensue. It's not only obnoxious, it's very tough on the axleshafts and u-joints. There are some nice kits available on the market that will allow the installation of front hubs, some of which cost nearly $800 dollars. Even after installing one of these kits, you would still have to stop and get out of the vehicle to lock or unlock the hubs to switch between 2 and 4wd low range. While certainly possible to do so, don't pull this on a group trail ride without expecting a rash of grief coming over the CB. The solution is a 2 low shift fork. Similar in benefit to the twin stick shifters available for older gear driven transfer cases that provide low range and front/rear axle selection with 2 different levers, the 2 low shift fork simply adds a 2wd low range detent to the existing shift pattern. Though not quite as flexible or as easy to install as a twin stick shifter, it's the best thing available for those of us with NP231 transfer cases.
We installed our 2 low shift fork while installing a slip yoke eliminator kit. Since either conversion requires splitting the transfer case halves, it only makes sense to do them both at the same time. Short of a set of snap ring pliers, there are no special tools required to install the new fork, although it is a time consuming piece of labor. Start by removing both driveshafts from the Jeep, draining the oil from the transfer case and disconnecting the transfer case shift linkage. With the transmission in gear, remove the front output yoke retaining nut and slide the yoke off of the output shaft. Move to the rear of the transfer case and unbolt the factory tailcone to expose the snap ring just behind the rear output bearing. Remove the snap ring and unbolt the rear output bearing housing, this will expose the oil pump. Disconnect the tube at the bottom of the oil pump using a small screwdriver and gently prying straight down; the tube is held in place by a small o-ring. Slide the oil pump rearward and off of the mainshaft and it's time to split the case. There are two odd bolts on the corners of the case halves, these must go back in the same place so pay attention during disassembly. Gently pry apart the case halves after all of the bolts are removed. Be very careful here, you will have to pry hard enough to break the silicone seal but be gentle enough not to break the aluminum case. Once the rear case half is removed, pull the mainshaft, chain, and front output shaft out as an assembly. This will expose the range fork and sector assembly. Replace the stock fork and sector with the Tera Low components and begin reassembly. Expect the installation to take the better part of the day. The work was easily done with the transfer case installed in the vehicle. Some people suggest pulling the case and performing all of the work on a bench. In the XJ, the difficulty of removing the case far outhweighs any benefits of working on a bench. The results of your days labor and $200? Greater flexibility and complete control of your existing transfer case. I've been running an Advance Adapters SYE with my 2 low shift fork for 6+ months now and it has performed flawlessly. The ability to shift between 2 and 4 lo without stopping is priceless. There are many times where you would just like to go slow on a rough road, but don't really need or want 4wd. This kit fills that gap perfectly. 
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