I need a rear drive and there are 2 that could be for my truck. One has a taper and the other does not. What is the taper for and what does it look like? I gave the Dodge dealer my vin number, and he said it has to be one of these 2. I want to try and find one in a junk yard, but want to make sure I get the correct one. This is a 2 piece drive shaft and all I need is the rear piece. Mine is bent from a blown u-joint. It's causing vibration between 45-65 mph. Thanks for your help!