Eaton Rear axle lubricant reccomendations?

[JonCBrand]

I have a 1989 Chevy with an Eaton rear axle.

Im not quite sure what lube this takes, its only a bit below the full level so im not to concerned but i figured why not change it.
Im thinking just regular old 80/90

[the_experience03]

The book for my Rockwell rear axle says 80w90. Unless you have a locking differential or maybe a two speed rear end I would just run 80w90.