It's an original RS4 with the rear powered by a gearbox. Here is the manual from HPI http://www.hpiracing.com/assets/manuals/143/143.zip
If you want parts for it you will need to lookup the part number in the manual, "follow" or save a search on ebay and pick up parts as they appear.
This is an old car and it will take some time for things to get listed for it.
Let me know if you are looking for anything specific.