the 10.5 takes 3.25QT / 9.5 2.7QT .. now on filling with the vehicle LEVEL in warm weather fill to just below the fill hole. in cold weather fill to 1/2in below the fill hole. this fluid when hot expands.Changed the fluid in the rear differential. The amount of fluid that I removed was ~2.25 quarts, and the fluid I put back in was ~3.25 quarts. I put fluid in until it ran out the fill plug. I wonder why the difference?
Used Mobil 1 75W-90 gear oil.
since you drained out A QT less then you must have a leak. check the fluid every oil change for level and fluid color.