CHICAGO--(BUSINESS WIRE)--Fitch Ratings has upgraded two classes of GMAC Commercial Mortgage Securities, Inc., series 2004-C3, commercial mortgage pass-through certificates and affirmed 11 others. A detailed list of rating actions follows at the end of this press release. KEY RATING DRIVERS The upgrades follow increased subordination to the first pay class attributed to the repayment of loans since Fitch's last rating action, while the affirmations reflect the otherwise stable performance of th