I think they are all the same , 98-2004 , I have both bikes and took the drum brakes off both and replaced them with disc , could pick out one from the other if I tried as I didn't mark them --------- I have had pieces of the backing plate where the o-ring sits break off and filled it with silicone or Honda Bond before , it really didn't matter as when you ride in water it is going to get in ------------ here is link to a used a plate with the arm and shoes for like $149 , PSN is usually pretty good on the price , but I seen that plate goes for $200+ new ----
Honda Foreman 450 S 99 Brake Backing Plate Rear 18326
Honda Foreman 450 S 99 Brake Backing Plate Rear 18326