Nope, don't have the fenders on mine yet.
3500HD always had an I beam axle. I currently have a 3500HD axle under my 48 6400 but it has been narrowed about 10". You won't really fit even the big bolt fenders over that axle, its at least about 8" too wide, something like 4" of tire hanging out each side unless you narrow it or stretch fenders.
However there were step vans and RV's with independent front suspension and the 10 lug wheels (5 up front). That version sounds like what you're trying to find. I don't know if they're any narrower than the I beam axles though.
