Question '08 DRW F350 Rear Axle Lubricant

[RoyRogers]

I just looked at the gear oil level in my new F350 Dually as I'm getting ready to tow a RV trailer. It looks to be low. The owners book is some what confusing to me as to which axle this truck actually has. Is the correct lub the 75W90 synthetic or 75W140 synthetic? Thanks

 

[atk]

rear differential uses 75w-140 synthetic. 75w-90 is usually for the front diff on newer trucks....hope this helps