to my knowledge those clips are a must! i wouldnt even think about puting 2gether a motor without them. if ur goin 4mil i wud suggest getting the FULL c clips from jeff at fast. Its a larger clip that secures the bearing alot better than the half clip. Idk how ur old motor survived so lng without them, lol.
** I have 5 or 6 of the full C clips (brand new) if anyones interested. Shoot me a PM **