For anyone needing to replace a lower balljoint on an earlier 5EXI, I believe this is the correct part:
http://www.ebay.co.uk/itm/Vauxhall-Cavalier-Mk1-1-9-RWD-Ball-Joint-Upper-RH-1975-1978-FBJ5045-/260912094429?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cbf929cdd
Front Vauxhall Cavalier Mk1 1.9 OHV RWD Oct_1975>Mar_1978 Ball Joint - Upper RH - Part No: FBJ5045
13 Jun 2012, 10:10pm