There a number of detailed threads on this subject. It all depends on how far you want to go and i f you are installing SSI's etc. I just did this on my 3.2 and kept the exchangers and cross over tube and purchased the left side socket and some aircraft hose. It works perfect.
I also purchased a used heat control module that I plan to modify to get the footwell blowers to work as well. A perfect mod to do before I change my fuel lines since it would have all needed to come out anyway.
http://forums.pelicanparts.com/showthread.php?t=220695&highlight=heat+backdate
http://forums.pelicanparts.com/showthread.php?t=417324&highlight=heat+backdate
http://forums.pelicanparts.com/showthread.php?t=388445&highlight=heat+backdate