Just installed the 4.56's..quick question about gear oil!

[BlackSilverado98]

The 4.56's in my 8.5" 10 bolt are installed and everything is done except when I went to get the gear oil, the instructions call for 85w-140. However the write up on GMFS calls for 80w-90. So what should I use?? Any help is appreciated here because I need this truck tomorrow morning. I already have the 85w-140 but don't want to put it in before checking....

 

[dcZ71]

for the break in period, i'd go with conventional 80w-90