Theres a thread somewhere about it and several lengthy posts!
Recap:
Gen 1 04/05
Front - ONLY 04/05 unless you want to start machining wheels and changing bearings.
A few will tell you its ok as Kawasaki have the same part number for front wheels, etc. Kawasaki have the same part number for the same parts on ALL their bikes - the first part anyway. There are another 6-8 numbers that then designate WHICH exact bike that part is for.
Rear - ALL models right up to 2015.
Gen 2 06/07 (underseat exhaust)
Front - ALL models up to 2015 EXCEPT 04/05 unless you want to go looking for bearings to match the smaller diameter front spindle. Has been done but not easy to source and usually only ceramic.
Rear - ALL models EXCEPT 11-15 - offset is different due to new swingarm design. Has been done but makes wheel changes difficult on the newer model.
Gen 3 08-10
Front - ALL models except 04/05 (see above)
Rear - ALL models 04-11 except 11-15 (see above)
Gen 4 11-15
Front ALL models except 04-05
Rear - only 11-15 due to offset, etc, Although it has been done in the States on 10R.net for cosmetic reasons, its a fuck load of works and very, very expensive.