As i looked at the parts from my XK compiling on my shelf, I wondered.... I have an XK with the 5.7L, tow package and 3rd row seats; So my vehicle probably came with the stiffest springs available for the XK/WK lineup.

Took a look at the parts manual and sure enough, there's a bunch of springs listed:

FRONT:
52124199AB [ZDB,ZSB]
52124200AB [ZDC,ZSC]
52124201AB [ZDD,ZSD]
52124202AB [ZDE,ZSE]
52124203AB [ZDF,ZSF]
52124204AB [ZDG,ZSG]
52124205AB [ZDH,ZSH]
52124206AB [ZDJ,ZSJ]

REAR:
52124209AA [ZBR,ZPR]
52124210AA [ZBS,ZPS]
52124211AA [ZBT,ZPT]
52124213AA [ZBV,ZPV]
52124214AA [ZBW,ZPW]
52124215AA [ZBX,ZPX]
52124216AA [ZBY,ZPY]
52124212AA [ZBU,ZPU]

I'm not sure what those codes mean yet.... but it begs the question.

For example, i'd guess that my vehicle has the stiffest springs and a 3.7L WK w/o tow package has the softest springs...

So I wonder, say someone with a 3.7L WK wanted a small lift, like 1"... If my springs would accomplish that, they'd definitely be worth a look considering there would also be absolutely no issues with warranty (i doubt a tech will be able to tell the difference in the springs).

Hell, if anyone with a 2005/2006 (or even newer) is interested, I have my struts/springs still completely assembled in my garage... they only have 35k miles on them so they'd make good replacements on the cheap for someone running 100k+ miles