depending on what motor mounts you have and how your motor is sitting.. normally the 90-93 axels are a little snug.. I have used the dust rings before on swaps and also had cars where it wouldnt fit with them.. I personally dont use them on my car.. but am also in the process of putting new axels together..89 integra shaft and outer knuckel w/ 91 inner knuckel= Sir axel
I guess it is more of a personal thing.. when all else fails fall back on what you know works..