I'm getting a little Chatter from my Posi unit.I tried doing the figure 8's on a parking lot to get the fluid to go up into the posi unit,no help.Rear has been completely rebuilt,has been fine for about 3 years.Just recently the posi unit has started to chatter on pulling out from a parking spot when I have to turn.I checked the fluid level,its fine.I guess the main question I have is what type of Posi fluid are you all using? How much Posi Fluid are you putting in ? Are you using regular gear lube with the posi fluid.?When I 1st had the rear rebuilt,I had the same problem,(I was using synthetic gear oil in the housing with Posi Fluid),I changed to regular gear lube with GM Posi fluid and problem stopped.Do you ever have to ad posi fluid to rear after a few years.There is no leakage at the rear of car,everything is clean,no sign of dripping or leaks.I've had this car since 1964,I never had problems years ago with any kind of chatter in the posi unit.Probably had over 12 different rears in the car over the years.Any help is appreciated. ****NOTE*** I had the same problem in my rear steer on my 2005 GMC Yukon.Rear end was changed out under warranty,when I got the truck back chatter was occuring.They changed to a different type of gear oil and fluid and everything was back to normal. John