'model years' for motors? like cars

[imstillatwork]

Where can I find information about which motors of which years where virtually the same?<br /><br />I am compiling a list for a web site and instead of stating (for example, not accurate..)<br /><br />1980 70hp<br />1981 70hp<br />1982 70hp<br />1983 70hp<br />1984 75hp<br />1985 75hp<br />etc...<br /><br />I can say<br /><br />1980-1983 70hp<br />1984-1996 75hp<br />etc...<br /><br />Does anyone have any information on this?<br /><br />Thanks!<br /><br />Kevin