HS30-H strongly adivised me to get the MK63 retaining rings, which used to be in the Nissan repair kit, but only has seals now. The retaining rings hold the seals in, and are very often rusty or bend when dis-assembling. They are NLA, but Vintagecraft makes reproductions, and sometimes lists on Yahoo auctions Japan;
https://www.vintagecraft-e-za.com/販売のページ/室内パーツ関係-シャシーパーツ/mk63ダストブーツリテーナー/