Peter Kohler wished to know the build timeframe of
Q 2689
Mine was Q3234, shipped in late late '74.
Part of a batch of 6 that came to SoCal.
So, that can possibly provide a not after time. Your guess as to production volume, Quinn in 1973 & '74 was getting much good press in Cycling.
If your "new" to you frame is the one recently on ebay, I looked at that and guessed '72 or '73 and repainted. the Original head tube transfer was much more finely detailed. The reproductions are not, and are admitted as so. Every Quinn I have seen had down tube transfers as well.
John Jorgensen
Palos Verdes Ca