Here is some info that my brother Dog posted awhile back: 5.9 mag balance is different from a LA 360. 5.9 uses an OE 5.9 flexplate/neutral converter. magnum imbalance is in the flexplate. LA 360 imbalance is in the converter. You've got some of this covered/dealt with but I wanted to get it out all there (more info the better). EDIT after (re)reading I wonder if they used the common LA plate as opposed to the 5.9 specific one?