This is what I found from a year of hard and frequent use outdoors with regard to the 1/10 pan diff. Anything you do to the rings is useless as the balls, on breakin, immediately cut a new surface (groove) to run in. If you spring for the $20 for the carbide balls, those and two to 3 sets of rings will last the whole year. The rings can be reveresed. I am running the original carbide balls. The diff is always smooth. Steel ball bearings will always have a little more roughness as they are not as hard to cut a smooth groove in the ring. Use green rubber seals to extend your bearing life.
The thrust bearing is a non issue. Radial ball bearings are designed to and will tolerate axial loads. The main damaging forces on these bearings used as a thrust bearing is dirt entry and brinnelling damage from crashes to the side. Certainly a non sealed thrust bearing would be worse in this regard as it would not have good seals. Brinneling would be the same if it was a ball bearing. A tapered roller bearing would be ideal for thrust but it would be heavy and large.
Run it just like Boomers Diagram. You need the Aluminum cone. You need 3 or so Belleville washers. As you stack these washers the spring tension is reduced much like stacking coil springs. There is no effective difference between the Associated TC diff which uses a stiff little coil spring or the Losi system which uses about 10 stacked Belleville washers. Both systems have good consistent spring tension.
Here is some Tech from Boca Bearings on radial ball bearings which is what we use in the diagram. We do not use full complement V-Type bearings.
"Load:Single row radial ball bearings with ball separated by a cage can support radial loads, axial loads and tilting movements.
All full complement V-type ball bearing can support only radial loads and some low axial loads.
Speed:Maximum permissible speeds for ball bearings are mainly related to the bearing design and size, cage type, bearing internal clearance, the method and type of lubrication, manufacturing accuracy, sealing methods and loads."