History... The Thermo-Quad (TQ) was initially released for competition in 1969. Chrysler introduced the TQ on the 1971 340. The first series of TQs including the 71 340 version and the Competition Series TQs were air metered units unlike like the 72 and later TQs which were solid (liquid) fuel metered. The Competition Series (CS) were available in 850 cfm and 1000 cfm ratings. CS units use a manual choke and have a minimal amount of external attachments compared to OEM production units. The CS was discontinued in the mid-70s. Carter released the 9000 series in the latter 70s as replacement carburetors for Chrysler and GM Quadrajet applications. The 9000 series was very similar to the production Chrysler Thermo-Quads. http://thedodgetruckforum.com/showthread.php?t=2352
