Depends on rust, really...
In all reality, you *should* be able to get it out and back in within a few hours. I'd say 2 at the most if it's clean under there.
Disconnect Driveshaft from diff.
Loosen carrier bearing bolts so it can slide forward.
Swing DS down.
Remove axle shaft nuts and bolts from diff
Unbolt diff from subframe.
Reverse to install.