Currently on eBay, item #Item number: 4594028327; is
"1969 Camaro Chevelle Chambered Ex GM Factory Bulletin
One 1969 Chevrolet Dealer Service Technical Bulletin covering the Chambered Exhaust System on 1969 Chevelle and Camaro SS. Covers the discontiuation of the chambered exhaust system on the Camaro and Chevelle, the interum design, and later replacement systems used. This bulletin could be very valuable in explaining differences on the way cars were equipped from the factory. 5 pages include part numbers, descriptions, and illustraions. Tech bulletin printed April 15, 1969."
Pictures are included. If the CRG database doesn't have all of the chambered exhaust info. it might need, this might be worth acquiring.