I have a 97 dodge dakota, 4x4 5 speed, 231d t case and im swapping the slip yoke. I noticed on the one i bought it doesnt have that huge circle ( maybe a weight) on the yoke, the one i bought( local shop found me something similiar since dodge doesnt make the one for my truck anymore didn't have that large circular piece. Is this something i need to take off the original and out on this new one

 

A vibration damper. Like a Harmonic balancer.
If the driveshaft is balanced properly you won't need it.