[woodridge]

To add to 69TowRigs statement that they are not seamless in operation, a transmission shop I used to work in was rack checking a tranny in a pickup on a drive on lift. They would set a jack stand under one side of the diff housing and run the tranny through the gears. The tech had run it up to about 50-55 which means the one wheel was doing about a 100 when the gov-lock decided to do it's thing. It sounded like an explosion when the axle snapped and by the time I got to the back of the shop from the office there was not a soul around and there was a madly spinning wheel creeping out of the axle housing on what was left of the axle, I made a quick exit myself. Fortunately the axle stayed in the housing and the wheel did not go on a rampage. It took over two hours to get the axle gear unramped so we could get the pin out and the c-clip off the replace the axle. So they are not smooth and if used much do not live long.