A quick jaunt through my 1960-1970 Motors Truck Repair manual(cocktail hour again) shows Dodge W100, W200, and W300(4wd) all using the 'big 6' lug pattern. It also appeared that the Chevy 3500 through 5000's used a large circle 6 lug pattern, but I've not seen one of those in person to verify if it's the same or not. Jim