I may be working a deal on a 2005 S4 that will need a timing chain job and understand the engine has to be pulled since the chains face rearward toward the firewall. The RS6 uses a belt but does it face backward too? You also have to pull the engine to replace the belt? And aren’t they the same basic 4.2 engine except for the turbos on the RS6? If so, why the difference? Did the later model S4 and RS4 change to front mounted timing system such that no engine removal is required for parts replacement? If so what years?