Just tighten the nut to 80 - 100 lb.ft and see, you have nothing to loose.
The manual states that if you exceed 140 lb.ft of torque you should change the spacer, and that’s because above 140 lb.ft you start to crush the spacer.
If you have the output shafts not connected to the diff you could try and measure the pinion drag with a scale while tightening the nut. I think that if your final measurement is about 5 lb.in more than your initial measurement you are in the safe side.