Okay, I've looked at some of the tabs for this song, and decided to put the REAL "CORRECT" version out there. Using 5th's, there's two ways you could play this song. But the way that Johhny Cash's band plays it, is the first version I'll tab. My band plays this song a lot at gigs, and it pretty easy and gets everyone listening. So here it goes...
B=bend; P=pull off;

INTRO:
G~|————————————————————————————|
D~|———————1—1——————————————————|
A~|—2—2—2—————2————————————————|
E~|———————————————3(B)——(P)0———|

THE REST OF THE SONG!! \m/
  The hardest thing about this song is the timing. The rest of the song is played with only two strings(or could be)!
#1
G~|————————————————————————————|
D~|————————————————————————————|
A~|————————————————————————————|
E~|—0—7—0—7—0—7—0—7—0—7—0—7—0—7|

Basically playing E and it's 5th, which is B.
#2
G~|————————————————————————————|
D~|————————————————————————————|
A~|—0—7—0—7—0—7—0—7—0—7—0—7—0—7|
E~|————————————————————————————|

Same here, except were play A and it's 5th E. See the pattern. 
#3
  1st position      2nd position 
G~|—————————————|   |—————————————|
D~|—————————————|OR*|———4———4———4—|
A~|———9———9———9—|   |—2———2———2———|
E~|—7———7———7———|   |—————————————|

First one is easier for me, because I don't have to move back and fort so much on the neck.

So basically you'd play in order of: 
#1, #2, #1, then #1, #2, #3, #2
If you listen to the song and play along, you'll figure it out pretty quick. Just watch the timing.  

For more advanced players**
You could try this instead of |0—7—0—7| you would use the octave above and the lower 5th. Same notes, just a different sound. I've played it both ways just to change it up.
#1
G~|———————————————————|
D~|———————————————————|
A~|—7———7———7———7———7—|
E~|———7———7———7———7———|

Then the higher A and it's lower 5th
#2
G~|———————————————————|
D~|—7———7———7———7———7—|
A~|———7———7———7———7———|
E~|———————————————————|

And #3 would stay the same. All in the same order of course. 

So there it is. I hope that someone finds this useful so that I didn't waste an hour of my time tabbing this. ;—) Good luck and enjoy!!