You can get away without using a "real" thrust bearing and just using a regular flanged bearing (like the kit supplies)
This works fine but you'll have to replace it constantly (like every 2-3 weeks, normally). This is because of the type of forces that we're putting on the bearing.
If your diff is notchy, first thing, replace that outside diff bearing - the one the cone/nut goes against. 90% of the time, that's the problem. It's easy, it's cheap (don't use fancy ceramic bearings THERE. . .just use cheap typical bearings since they're GOING to go out. . .).
RC10L2.5W - RC12.4 - RCNTC3(bmi) - TC4 (modded) - B44.2 - plus rent-a-rides! :D