What is needed to change the gearing in the M37. I have never been inside the rear ends. I know that my rear pinion will screw in and out so it will need to be fixed. I don't have the truck here to look at. I saw a gear set that says it will change the ratio from 583 to 489. The PIC of the gears did not have a ring gear. Does the Dodge use a ring gear or will the internal gears change the ratio.