This double row bearing has a notch [or opening large enough for a ball] for inserting & assembling the balls in manufacture. This bearing should be installed with the notch's up. This puts the loaded balls riding on the notchless races. Picture it in your mind, it is real simple. Of the many I have checked over the years, about half were installed right and half wrong. It is not a life or death deal. That bearing even with notch will support 10 times our loads. To check a bearing, carefully pop off grease seal and look for notch.
Don't trust direction of printing, most are foreign made even with U S name on box. Do not over grease either. Use a good pressure grease. We will never wear one out if properly packed. If water gets in bearing from rain or what ever it can rust and be ruined. Every time rotor is removed, give it a spin with your ear near...