Hi All,
Here it is from the Ford MPC. The 1965-66 GT350 had a unique part number for the proportioning valve C5ZX-2B091-A. The ZX combo of letters was commonly used with SAI programs, according to Bob Gaines from a prior post. Bob said "I thought I would mention that the ZX is most commonly associated with Shelby as in C5ZX,C6ZX,C7ZX,C8 etc. The ZX parts are only serviced for shortest periods of time it seems." This piece was also not serviced (at least in 1975), based on the below comment "Not replaced".
Hope this helps.
Cory