This is a transmission tailshaft bearing with various applications.  It is used as the tail bearing for the following:
MGB LH OD tail bearing
Triumph Spitfire J-type OD tail bearing
Triumph TR3-TR6 & Stag standard transmission tail bearing
Triumph TR3-TR6 & Stag A-type OD tail bearing
Triumph TR6 & Stag J-type OD tail bearing