two words: "penetrating oil"

just seeing the rust gives me the heebie-jeebies. Getting the corroded aluminum and steel apart will be a challenge.

On the other hand, I used to have a Raleigh Gran Sport, and loved how well a Stronglight 93 crank would polish up! Beautiful!

Steve in Peoria
(penetrating oil, lots of it, and frequently reapplied)
(good luck!)