You want to get the thrust type ball bearings (they're the ones that have the races at an angle relative to the shaft so that they can take some thrust) and that's really the best way. Next best are tapered roller bearings which also take thrust. You put the bearings in so that you can take up a positive tension on the shaft and thus take out any slop in the bearings. All you need are a few ft.lb. of tension to do the job. A nut on the end of the shaft only needs to have 2-5ft.lb. of torque on it to streach the shaft well.