well, in my interchange manual, HCC-AW calls for a manual box used for 64-1/2 - 67 mustangs and 67 cougar with 16:1 ratio. hope this helps.
Rubelle
65 2+2, 289 (early A code), c/r toploader, magna suspension, centerline convo pros
Rubelle
65 2+2, 289 (early A code), c/r toploader, magna suspension, centerline convo pros