Far as I know, the 6-bolts never were setup other than the drums bolted to the inside of standard hubs. Those used two spacers behind the hubs to get the hub out the thickness of the hub for brake clearance on 5000/Pros. The 4 bolts only used one for all uses and couldn't use two there as the axle was too short. Gravely knew there was a clearance problem with the 50" decks and dual 4-bolts and said that the 4-bolt hubs had to be changed to 6-bolts and spacers. L-1786 5/1995.