My drain and fill plugs on the transfer case puzzle me. A 10mm hex key fits in the fill plug with a lot of slop, but doesn't fit in the drain plug at all. They look like Torx keys, but they have 8 points (Torx is 6 points, right?). Anyway, is there a special tool for certain model years or cases? This is a NP241D unit in a '96. Could it be that some technician boogered up these plugs at the last service? Thanks