Brake help

[Stephen717]

Ok so I'm trying to get the drums on my ho52 axle, I've upgraded from what was on there to the 14 bolt drums as I've seen other members do but when I get the drum seated there's an inch between the backing plate and the drum. The hub is seated fully and I'm not sure if the original Eaton hubs are to shallow for the 14 bolt drums or what could be wrong, any help would be greatly appreciated. Trying to get this done today so I can temporarily roll the frame out and have more room in my shop.