A long time ago....a LONG time ago, I broke a front tower on my car, and didn't have a replacement. My buddy and I talked it over and decided to try a rear on the front, just to see what would happen. Turns out, with a diff, it gives the car alot more steering. The only problem was that you couldn't lower the front of car below 5mm. We sent the info to the team (they were at the 2000 Worlds...I think it was the Worlds) and they tried it, and liked it, but because they couldn't get the front to go below 5mm, the rear-tower-on-the-front was scrapped. Now, here, at the 2002 Reedy Race with no one-ways (dual-diffs), this came back up. Running the rear tower on the front gave us alot more steering, but, again, you couldn't lower the front of the car below 5mm. Enter the new front arms with the extra hole. The new hole basically makes the shock position the same as if you ran the standard tower with the standard arm hole, and you can lower the car below 5mm.
It makes the suspension (front and rear) symmetrical, and puts the leverage farther out on the arm. It's not totally necessary to run this setup with dual-diffs. The setup we came up with using the standard tower (at the Reedy Race) was comparable, this just felt a bit faster.