Outer Limits 4x4 Board

I have 2 spare diffs laying in the garage and was wondering if they are OK just wrapped up in a towel or do I need to store them in oil or diesel or something?

Dont want them stuffing up b the time I need to use em..

wrap them in plastic, rags will eventually wick all the oil away and they will rust on the gear teeth. wrapped in a couple of big plastic bags, in a milk cratefor mechanical protection is a good way to store diffs.