The wiring harness is different. The '97 uses two wires and the later (slower) ones use 3. You can easily make one yer damed self and even make a switchable one so it can run like stock or without the retard in the lower gears. The only reason I can think of that you would want to have it switchable is if you were riding in very hot weather and the bike wanted to detonate. Other than that I don't see no reason to have the stock retard circuit at all.
If you are mechanically reclined enough to make it yer self then hopefully the nice person who sent me the diagrams on how to make it would do so again or I can maybe find the link. You will need a 15K ohm resistor, small not much wattage needed, small gauge wire like 24 or so and a Single Pole Double Throw switch, SPDT. No momentary or Center Off option. Some heat shrink and be able to solder it or have someone to do it fer ya. Some bullet connectors would also make the install slicker. Pick a switch that will mount where you want it. I'm not gonna mount mine where it is real accessable cuz I don't think I'll need to change on the fly.