As John said, get yourself a parts book. How else would you know that you've got the correct track rod? There are four different ones you can put on,however only one of them is the correct one.
Series 1
Series 2/2a pendant type ball joint
Series 2a non pendant type ball joint
all with recessed thread but the rods are different length, and
Series 2a/3 ?? with the thread to the end.(I don't have one of those in front of me, so I can't comment on the length.
W.

