Expert X.
The 2004, 2005 600HO's have a four inch taller seat height then the 503F's, the 2006 trail models with the flame decals had two inch adjustable rear suspension mount holes.
This repositioning by drilling new holes back is also a way some of the Hawkers, and owners of the the expert suspension system could longer track their machines I/E 136" - 141" without new rail extensions.
For the tall riders "Extreme Hawk" has come up with drop peg mounts, every body I have had try are not sure at first, their worried about dragging their feet, after a day of riding them their sold, tall or short riders!
While I'm at it a taller seat flush with the gas cap, like a modern MX bike does wonders for keeping away leg cramps on us 6'5" +-er's.