Text to date format
 

I have a large file imported from another source into Excel (2003) with a
column of dates. The date column format is eg Mar. 09 1963 but some dates
only have the year or no date. I want to convert dates to format dd/mm/yyyy
or where there is no full date, to return just the year yyyy. Where the full
date is available I can convert using formulas or Text to Column, but I have
trouble where there is just the year. Is there a method without having to
convert manually all the dates with only the year?