New gears and alot of noise

I have just recently put together a 742 case with strange 4.11's and sure grip and it says the gears have to broken in, first with the rear in the air and then drive for 10 miles but as I had the rear in the air there seems to be alot of noise. Could it be that the diff was dry for so long? I put royal purple 75W 140 gear oil in it. could that be my problem? I know the backlash and pinion depth are right. The instructions from strange say there is some noise to be expected, but I am wondering how much is acceptable?