I've had two power locks on my jeeps and they were pretty good limited slips. What I liked about them compared to the Traclock is that they were significantly beefier and more positive then a trac lock. The power lock has a four pinion spider gear compared to the traclock's two. This is inherently stronger. You could also set the Power lock up pretty tight, tight enough to roll my jeep foward with one wheel on the ground. The drawback is that it is a clutch type limited slip and it does wear. I put around 20000 miles on mine and it was pretty loose towards the end. I now run a detroit in the back and a power lock int the front. As for sources, You might try Randy's ring and Pinion, and also Drive train specialists. Good luck.
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01. 5 ETH/DEE QC, 2500 4X4, 3. 54 Everything but leather, added SPA Boost/EGT guage.
68 Jeep CJ5, V6, 225ci, sm420, warn overdrive, full floating detroit locked 44 in back,
2. 5" superlift, power steering, 4. 88gears. Mobiweld welder and other neat stuff.