I am currently working on a Monza Junior with the Series 1 rounded bodywork. I wanted to upgrade to 17" rims front and back to increase the height a bit and found a nice old alloy rim with rear hub and brake on eBay. Below is a picture. The hub appears similar to the stock Ducati item but the cush drive/sprocket carrier has dual sprockets mounted. I assume this is for offroading. So, is this hub from a scrambler? If not, anyone else know what it may have come from?
Here's what I'm working with:

Here's some pics of the rim, hub, and brake:


