the only steering dampner I know of fits the 700.Its made for a king quad 700 but I have herd of some being put on the ac 700.Not for sure if it is a direct fit or needs modifacation.
The AC's steering geometory is such that it suffers from alot of bump steer. IE if you hit a good size rut or log with only 1 tire there is a good possibility that the handlebars will be riped out of your hands. Sprain wrist or worse can happen pretty easily. What it does is resist quick movements of the handlebars. Same as a steering stabalizer on your car or truck.
i think the one Darrell runs is a precsion with adapted clamps.i was thinking of getting them to do me one if i get to hit some of the quad terrain challanges.
Lot's of discussion on the Outlander800.com forum about the stabilizer from Precision. The few guys that have them are very excited about them. Much easier to ride and ruts don't wear you down after a day's riding. Pricey though at $500. Don't know if they make one for the Cat.