This is the O ring that seals the cam follower to its housing 1966-1980 Silver Shadow, T-series, Shadow II, T-2, Silver Wraith II 1980-1995 Silver Spirit, Silver Spur, Mulsanne, Turbo...

This is the Brake Pump Seal Kit (Before Vin#8427)  After #8427 See RH2897GMF kit Note: Also will need GMF1023 per pump 1980-1983 (Vin 1001-8427)