Originally Posted by no1gxl
is it really that important? The numbers on the 4v's are all covered once on the motor anyway..!!!!!!
It is important if you're restoring a car with correct dated parts, and to claim a set of heads are phase 3 is almost impossible to prove because they're identical to all other 4V heads bar some machining and the date codes.
Phase 3's used the same 4V heads as the other 4V GT's did, they just modified them for the adjustable rocker gear.