Steering box - Which lubricant?

OK, I just finished my whole front suspension rebuild, and it'll get aligned first thing in the morning. But I waited to check my fluid in my manual steering box because I figured it had to be in the installed angle to determine anything.

The factory manual says nothing about what type of lube to use. The Hanes says SAE 90 Hypoid GL-5....mine appears to have grease in it........

I bought it from a club member, and it looks to have had minimal (if any) use. There is minimal play, and the input shaft could be turned by fingertips to operate the box. The cars steers awesome (for a stock ratio box).

Is there something I don't know here? Is it some underground fact that it's better to put grease in these things?