Driveshaft yokes

[KMAT]

Since I have had such good luck will try one more time everybody has been so helpful okay so I needed a length in my drive shaft inch and a half went and got a longer yolk from the salvage yard which will work but it has this round like vibration dampener attached to it. Question is should I use it and leave it on does it come off or not use it at all any information would be much appreciated I will try see if I can figure out how to attach a picture once again since I forgotten go figure.