I have been looking around, biggest I can find in the 8 lug flavor are 2" wide.
Usually made of aluminum.
I did find some at the junkyard on a 14 bolt that make it so the face of the wheel sits roughly even with the flanged end of the axleshaft. Apparently some older ambulance conversion have them. They were made out of some sort of ferrous metal (forged I'm guessing), but the junkyard man insisted they were part of the axle that couldn't be removed, and he wanted $300 for the whole thing. Yes, this is the same junkyard I got a D60 front at for $150. *sigh*