Hope someone can shed some light on this for me. I just called my local Hustler dealer for pricing on an Air Filter for a 23hp Kaw. Z (8yrs old).....he said the inner is $x and the outer is $y. I replaced the original filter once before and it did not have an inner/outer combo on the filter or did I have inner/outer on the replacement filter??? He stuck to his guns and said you need both. Here's where it gets even more interesting, the Kaw manual shows some sort of foam slip on over the paper element, but the Hustler manual calls for a Donaldson filter (part 785261) which has no slip over outer element. Can someone tell me which is correct and maybe even a link to the correct filter. thanks!