it depends on the casting..... F6te are gt-40's and f7te are gt40p
in Fords part # system a letter designates the decade c=6 d=7 e=8 f=9
followed by the year produced. E7 heads were produced in 1987... that doesnt mean that all E7 heads were made in 87 but thats the same casting through 93.
F6 heads are 95-96 Explorer gt40 cast heads. F7 is the updated better flow fastburn GT40p heads 97-02 explorer