the RS4 RTR 3 was replaced by the RS4 3 18SS, 18SS+, EVO and EVO+. It still uses the same chassis and everything as the 3 RTR, just has different engine and 2spd trans.
You can get alot of parts from RCBoyz on ebay, .. and here
http://www.asiatees.com/model.php?HP...&model=RS4%203