Hello, I had been having trouble with my CAD on my 88 YJ and after troubleshooting it I determined that the shift fork was too gummed up to move by vacuum power. I was looking at purchasing a Posi-Loc from Rusty's but instead wound up going with the Permaloc. The only difference is that the Permaloc permanently locks the fork in position to lock the axles together all the time while the Posi-Loc has a cable actuator which allows the fork to disconnect the axle shafts for street use. I had previously installed a Posi-Loc on a friend's Jeep and the install was very simple but because the Permaloc doesn't even have a cable actuator to run into the cab it was even easier. The hardest part is removing the aluminum fork from the stock CAD solenoid as the E-clips can be difficult to remove off the shaft. The only downside to the Permaloc is the increased wear on the front axle (its similar to running a CJ with the hubs locked at all times). But if you don't use you YJ as a daily driver its a viable option, especially because its half the price of a Posi-loc and only take about 30 minutes to install. All the parts are quality (and beefy) and the instructions were very well written with good pictures. Just thought I'd share, as I was unable to find anything on the Permaloc through the search function.