The thicker basket, with the double plate in the center, is from a later model (K7/K8/F2/F3). They do indeed have one plate that is different than the other six. Also, the stack ends up being about 1/4" taller and will require some clearancing on the inside of the early model clutch cover to prevent interference. I found this out when I used an early model clutch cover on my K8 (it was shiney!) but when bolted in place the clutch wouldn't budge. Requires removal of some material on the inside of the early model cover in a couple of spots.