Here is the chart for the front springs and info on the rear springs. From JKOwnwers:
"[A]ccording to the Jeep service manual figure 2-110 all front spring numbers start out 521263 the only thing that changes is the last 2 digits the first spring being 52126310AB the last one is 52126318AB from a large response to this on another forum depending on many variables from 2dr to 4dr, tow package, hard or soft top, fourth digit in the vin being "F" or "G" will determin what springs your jeep has. There is reported to be a 1/2" difference between each number [more like 1/4" - 3/8".] so by that understanding if you had front springs that ended in 10 or 11 and you "upgraded" to springs ending in 17 or 18 you should in theory get approx 4" of lift depending on the wear and tear of the springs you got. The discussion also shows that the front springs wil have a left and right. so you jeep could have any combination of:
The larger number should go on the Passenger side to compesate for the fuel tank.
Now all of that being said my 2008 X 4dr with a hard top and tow package and a "G" in the vin came with springs ending in 15 and 16. I was able to aquire a set of rubi springs that are 17-18 so when I switch my springs in theory I will gain 1" in the front.
The rear springs start at 68004250 and go to 68004260s in matched pairs. here is where it can get weird or confussing 68004250 should be the shortest / softest springs and 68004260 should be the highest/ firmest spring. My jeep had 4257's on it and the doner rubi springs are 4255's so I will not be swapping the rear springs." [Clearly the Rubicon didn't have the tow package.]
Here's a link: http://www.jkowners.com/forum/showthread.php?t=9492&highlight=rubi+springs&page= 3
If you search for "Spring Chart" you will find a number of threads on the topic. From all reports the highest rated springs come from Rubicons with hard tops or dual top options and the tow package. But even the X's and Sports with tow packages have higher rated springs than their non-tow package counterparts.
There are photos on the linked thread which show the results of installing the higher rated springs and the results range from a little lift to a substantial amount. Substantial for a four door Rubicon hard top with tow package to four door soft top X without tow package swap. Seems about 2-2.5" is the max four door to four door result.
As I mentioned previously, the springs can be identified by a tag on the spring. But the tags can come off since they are merely foil tape wrapped around a coil with the number and, iirc, a bar code.