One of the best CDs recorded anytime, anywhere, Unchained takes Johnny Cash, backs him up with Tom Petty and the freaking Heartbreakers, and then sets him loose to perform covers and original songs (many written for him by Tom Petty).
As you can imagine with a lineup like this, it's pretty damn good.
"Rusty Cage", a Soundgarden cover. Rarely is a cover better than the original. Even more rare does a cover completely destroy the original and make you never want to hear it again, preferring the cover.
I'm not sure if this says something about Soundgarden, but I'll give them the benefit of the doubt and conclude that it's just that Johnny Cash is that good.
"I've Been Everywhere", the Bob Dylan classic. In this case I again have to conclude that the cover is better than the original. Here the Heartbreakers really show why they are legendary band, and Cash's baritone is never more full of life than on this track.