I have seen this once on a 1981 shovel. We cut it apart to see how it worked. If I remember correctly it had three rollers like in a needle bearing that slide up ramps and jam against the shaft when turned it on direction and they slide down and release in the other direction. Pretty simple.
I replaced another one on a 84 softail with a 113 S&S that was slipping with an All Balls one and it still slips when motor stops on the compression high side. He has to put it in gear and bump the engine over to get it off the compression high side then it will start.
I replaced another one on a 84 softail with a 113 S&S that was slipping with an All Balls one and it still slips when motor stops on the compression high side. He has to put it in gear and bump the engine over to get it off the compression high side then it will start.