And by preload, you mean the force (in inch/lbs) it takes to rotate the nut/yoke/pinion/pinion bearing assembly without the ring gear and carrier installed, correct? This requires almost full disassembly of the differential to do this test.
Just want the OP to be clear in his understanding, as the torque on the nut itself may exceed 150 FOOT/LBS (not inch/lbs) to actually crush the sleeve the correct amount. So it appears that you set pinion bearing preload by crushing the sleeve as you torque the pinion nut. Then you verify the setting by testing how much force it takes to rotate the pinion, before you install the carrier.
https://www.stevesnovasite.com/threa...g-seal.124301/