Not sure on Dr.Diff's bearings but I'm sure Cass can tell you if you just ask. IMO you need the inner seals. The o-ring is on the outside of the green bearings which will prevent lube from seeping around the outside of the bearing and the bearings are sealed but I have seen those seals fail (in other applications but the result is the same) and let gear lube wash the grease out of the bearing ruining it and your brakes. For that reason I always install the inner seals. There are a few different widths of 10" brakes. I know of the std A-body 1-3/4 wide units plus I've seen 2-1/4" and 2-1/2" wide shoes. I think that's it but not positive.
