Thanks for the feedback. I based the April 1969 date from Jerry MacNeish's book, The Definitive 1969 Camaro Z/28 - SS396 Fact Book, pp. 37-38 where he explained the time line with a sketch showing the three different 1969 exhaust system configurations. Also, on pages 114-119 he shows copies of original window stickers and car shippers, and explained the standard price increase for the Z28 option during the May 1969 time frame, from $506.60 to $522.40 due to the standardization of chrome tips. Based on the 05A build data and VIN number of my car, it fits in between the window stickers shown on page 111, a May car with VIN 637170 showing the $506.60 price point, and the window sticker on page 114, another May car with VIN 652055 showing the higher$522.40 price.
If anyone else out there has a May '69 Z28 built at Norwood, and happens to have your original window sticker, I would like to know what the price was for the Z28 option, your VIN number, and if know what exhaust system originally came with your car.
I would like to share that Jerry MacNeish goes on to quote a letter sent to Chevrolet dealerships on 12/23/68, stating that the cambered exhaust was discontinued as the standard system on 11/25/68. This was due to citations the police were handing out for excessive noise on Camaros (and SS Chevelles) optioned with RPO Z28, L34, L78 and L89. The chambered system was replaced with the standard duel exhaust system used on the 396/325 HP, L35 Camaros. The letter goes on to state that the RPO NC-8 chambered exhaust was still be available as optional equipment in "those areas where this system was permissible", then finally deleted from production on 5/19/69 with the standardization of the chrome tips. Interestingly, the window sticker shown in his book on page 113, Z28 VIN 641676 destined for Clinton, Iowa (the Iowa Governor at that that time must have been a Camaro fan....) included the optional chambered exhaust for $15.80.
Sorry for getting a bit wordy here but wanted to pass on to others what I have learned, who may not yet have MacNeishís and other related fact books. Letís keep digging for and sharing more factual documentation on this topic! I take loads of pictures of any unrestored 69 Camaro I run across but have not yet seen an original exhaust system.