Acceptable date codes - 1969 427 COPO Camaro

[R68GTO]

Posted this over at SYC also.....Trying to track down a few items for my car (09D 1969 Camaro) and notice a lack of parts dated July-Sept. of 69. I've read that the 499 dizzy was last produced with an April date....what about things like 163 intakes, 837 alternators, 291 heads, exhaust manifolds, starters, etc. Was there a gap in production at some of these manufacturers due to the 1969 design carryover into mid-November? Any insight appreciated!
Jim