When was the last time both Michigan and Michigan state were undefeated when they faced each other?

Coming from the Spartan side of things, we've always been rivals. When the State of Michigan wanted to create and agricultural college, the University of Michigan fought against it (despite the fact that the school was near failure - obviously, they bounced back). U of M also voted against Michigan State's entry into the Big Ten (then the Western Conference) in 1953 and against it becoming a University in 1955. The Paul Bunyan trophy, the rivalry trophy in football, was created in 1953. And let's just say things have gotten worse on the MSU side, who is tired of being outshined by U of M despite the fact that we, too, are one of the best universities in the world.