Is there easy way to set the 20 inch pounds load on pinion nut?

[Curt Campbell]

Book says set the first large nut on driveshaft for preload at 10 inch pounds....the when 2nd nut is tightened and the lock washer between them is bent over you should have 20 inch lb preload on pinion. I nor anyone i can find has any equipment to do that.

How do you guys set it...surely a hand guess method that is close!!!!!

Thanks....I am more than anxious to put this diff back in