The contributions of this paper are new 6-round impossible-differential (ID) and 9.75-round known-key distinguishers for the 3D block cipher. The former was constructed using the miss-in-the-middle technique, while the latter with an inside-out technique. These are the largest ID and known-key distinguishers obtained for the 3D cipher so far, based on the fact that complete diffusion is achieved after three full rounds. Thus, we exploited the slow diffusion in 3D to attack the largest possible number of rounds. The ID distinguishers lead to improved attacks on 10-round variants of the 3D cipher, in the single-key (non related-key) model. These results represent the currently best attacks reported on reduced-round 3D cipher.