I actually remembered reading the reason why the 6.1L couldn't have MDS shortly after the 6.1L was introduced. I believe you are right, Jeremiah, that the 6.4L will only have it with the automatic. At this time in the case of Chrysler, it is being used as a crutch for the inferior Mercedes W5A580 transmission. The manual doesn't need it because it has the ability to have both tall gearing for fuel economy and a reasonable shortness for the combined first gear; whereas, the Mercedes W5A580 transmission is geared too closely to where it requires the engineer to choose between fuel economy and acceleration.