Exhaust ring, by Bristol Siddeley Engines Limited, Bristol, Gloucestershire, England, 1967-1972. Used for Gamma 2 rocket engine (2nd stage Black Arrow type), by Bristol Siddeley Engines Limited, Bristol, Gloucestershire, England, 1967-1972. Used for Gamma 2 rocket engine (2nd stage Black Arrow type), by Bristol Siddeley Engines Limited, Bristol, Gloucestershire, England, 1967-1972. Exhaust ring, for Gamma Type 2 engine, c. 1968. 1967-1972