Does my 6904 have the Novak sights, or are they the S&W 'pre-Novak' sights? The low light Trijicon SA05 sight is for the 'pre-Novak'; while the SA08 sight is for the weapon with Novak sights.
From a machining standpoint. To convert to the Novak sights, you mill off a few thousandths behind the rear sight. Pretty simply for a machinist with an end mill. The dovetail on the front is the same and the rear is the same angle.