Stephen,
Heres a pic of series 1 arms, you can see the difference when the front arm is at the back and back at the front as Ive layed the left hand side on top of the right hand side:
Heres the series 2\3 arms I have:
See how they kink in a bit just after the pivot bolt thingy (technical term). The difference between using series 2\3 arms (which are the same dimensions front and back) and the series 1 arms, is that the series 1 arms will place the upper ball joint 8.5mm further back.
The jury is out on whether series 2\3 arms come in a "straight" design, the place I got mine from said that they had not seen series 2\3 arms straight like series 1.
Cheers.
