You can get the 2 bagger. The 3 bagger is for the 2000 and 3000 series with 44" deck.
I have owned the 2 bagger on my 1515, then sold that for a 2180 and have a similar 2 bagger on that. The baggers on the Cubs are awesome. I bag my lawn in spring and dump it in my garden for compost. It gives a nice professional cut. If you have a place for the cut grass, it is money well spent. They really pack the grass in. Keep the mulching blades on too, you won't need the high lift blades. You'll actually get more grass in the bag with the mulchers. /forums/images/graemlins/grin.gif