NET
6 who made us adequate to be servants of a new covenant not based on the letter but on the Spirit, for the letter kills, but the Spirit gives life.
Darby
6 who has also made us competent, [as] ministers of [the] new covenant; not of letter, but of spirit. For the letter kills, but the Spirit quickens.
KJV
6 Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.