I got a 6.9 idi ans a c6 transmission i was looking at a manual shift valve body can someone explain to me exactly what this does a x whats the best i want to get a floor shifter from american shifter or lukor and was wondering if i could basicaly use that and shift manually with the shifter. How would thag work my colum shifter only say 1st 2nd drive would that be 1st 2nd 3rd on a manual valve body?