Detroit locker posi unit??

I have had a Detroit Locker in my Ferd for over 15 years. When I ran the 5 speed, I noticed the slack too. That is just the nature of the beast. You can always tell a car equiped with a locker by just rolling the car back and forth 3" with the car off and in gear. When I switched to an automatic, I stopped noticing the slack. You can still roll the car back and forth 3" with the car in park.