You can now get the 5 speed header drive in the 9770's. Also, the fan set up is IDENTICAL, just a adjustment stop is changed and voila...1350rpm. I also added the ICC to my 9770 for very little money so for all intents and puposes it is a weak knee'd 9870 spec for spec. In our conditions, our 97's are not limited for power, but we run out of capacity other places so I went with the 9770 plus ICC. BTW, it bolts right in.