Steely Dan

we're riding out the 90+ degree heat @ homer's, and listening to steely dan right now. steely dan is basically donald fagen and walter becker, with a revolving cast of studio musicians. there was another adjunct band member with a very distinctive voice who appeared on at least two records with fagen and becker. do you know who it was?
a) Peter Schilling
b) Joni Mitchell
c) Michael McDonald
double punches today if you get it right! oh and the answer to last wednesday's trivia is squeeze.