On all the Ferris's we have seen, there is a 2" tall rib that runs across the deck: 4.5" - 5" from the edge. Due to this rib, the 'SLIM [HD]' Model is recommended for Ferris mowers. For those who want The Original Green Guard, the original model fits well (slim not necessary). As seen in the above photo, the rib on the Ferris deck will sit between the Green Guard base and motor. You will just have to raise the base 1/2" using the included spacers. Our magnetic 'no-drill' kit works well on the Ferris.
These are the Ferris models we have verified 'The Green Guard' will fit on:
IS 6200 ICD 72" IS 700Z 52" and 61" ISX 800 61"
IS 3200Z 61" IS 600Z 52"
Ferris Standers Z2 & Z3X (Pretty sure it will fit Z1, too.)