The Drill is a DW980K, although many other drill models will also work.
The XRP drills are good because they are easy to mount with the extension ring for the optional handle.
You can order parts from DewaltServiceNet
http://servicenet.dewalt.com/Products/Detail/DW980K-2
BTW, RS-775 motors will drop right into this drill with no modifications at all if you have the tools to swap the pinion gear.