Well Adam the only way to be sure is take the nut off the lower ball joint
and check the thread diameter, but failing that, and if you know the ball
joints have never been changed:
The 9/16 ball stud has a nut that is 15/16 across the flats.
The 5/8 ball stud has a nut that is 1 and 1/16 across the flats.
Your 1994, unless it has been modified has the 9/16 stud.
If your 1995 was built in July of 1995 you MAY have the 5/8 stud. I have not
heard of any June built 9C1s with the larger stud, but I don't have a lot of
responses to that question either. Look on the label on the driver's door
jamb for the month and year of assembly.