I think I know what you are on about , does the nut look like this http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=310298586991
If it does you will need to buy new ones as they are only suposed to be used once as they can split up and just spin around.
They was fitted to the later ford fiestas mondeo and escort but there are different sizes.
Hope this helps