You can see my modifcations in my Brickshelf folder when it's public: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=487667
I did only some small mods:
- black wheels with center caps
- modified lights and some additional lights
- modified exhaust
- mechanism for unlocking the cabin
- widened bed 2 studs
- widened the mudguards for maximum trackwidth
- some extras (snow plow, grass mower)
- extra rear lights for the crane
Only some small mods, but i think it's looking more realistic with them.