Phil
It will probably be ¼ inch UNF. The remote greasing kits supply M6/UNF/BSF nipples for the stub axles. The pitch difference is only 26 tpi to 28 tpi (UNF is 28) Try
www.lubetec.co.uk for 45Deg hydraulic nipples.
I fitted the UNF to my 2001 Y reg 4/4 Zetec with no problem. GOMOG and Morganatica have good information.
David
