There's a little groove for the end stroke rebound adjuster to "fit" into at bottom out. So basically, if you look on the side of the link where that would sit, you'll see a little groove machined out... and because of that, the link is not perfectly symmetrical (given the adjuster is on one side of the shock).
The 07 link is identical except it has no such groove, and therefore the link is symmetrical.
The 07 link is identical except it has no such groove, and therefore the link is symmetrical.