This complicated question has bugged me for about 3 to 4 weeks now.

First background info:
In an episode of Naruto, where Sarutobi was fighting Orochimaru, Sarutobi did this one special jutsu in which he summoned Death. He starts extracting Oroshimarus soul out and says that that is the jutsu that Yondaime used against the Kyuubi 12 years ago while sealing it in Narutos body.

Now for the question(s):
Sarutobi said that that jutsu kills not only the one being attacked but also the user, and that makes sence since Yondaime died, but if yondaime was the user shouldn't the kyuubi be in him and not Naruto? What was the name of the jutsu that they used? Shouldn't Naruto be dead?

I'm an extreme hardcore Naruto fannatic but thats the only question I can not answer.