The amount of balls in an over was not standardized internationally until the 1979/1980 season, but since then, all test cricket has been played with six balls per over. Prior to this time, most countries had different systems, notably Australia and New Zealand, who had 8 ball overs whilst England and most of the other cricket playing nations had 6 ball overs. England, for example, had tried many lengths of overs until it was decided that six balls was the optimum. Generally each country would use the over system which was in place in their domestic cricket leagues.
Balls in an Over
England -
1880 - 1888: 4
1889 - 1899: 5
1900 - 1938: 6
1939 - 1945: 8
1946 to date: 6
Australia -
1877 - 1888: 4
1891 - 1921: 6
1922 - 1925: 8
1929 - 1933: 6
1937 - 1979: 8
1980 to date: 6
South Africa
1889 - 1891: 4
1892 - 1899: 5
1903 - 1936: 6
1939 - 1958: 8
1962 to date: 6
New Zealand
1930 - 1968: 6
1969 - 1979: 8
1980 to date: 6
Pakistan
1955 - 1973: 6
1975 - 1978:8
1979 to date: 6
The other test playing nations of India, West Indies, Sri Lanka, Zimbabwe and Bangladesh have always played with six ball overs.
