Just the center, but it's a bolt through design, Supposed to be good to 1500hp they said. It's way overkill for my 200hp engine but I wanted to only buy this stuff once. I figured with buying gears, bearings and through them I had about $700 into it. But I paid a bit more for shipping as I thought my gears were fine when I bought everything, so I had to pay shipping for the gears later.
I am using a Currie carrier in mine, that swapped over from my old center section. Everything else was new.
They have iron center chunks for cheaper.
The distributor I got it through was here:
http://stores.ebay.com/Quick-Performance-Inc they are in IA, and I got everything in 2 days after ordering it. I got better prices after calling them then they had on ebay
If you don't want the bolt through design one they have a regular aluminum one for $250 it looks like.