You need to mark all the parts of the driveshaft or propshaft before removal .If its fitted wrong you wont get the balance right .You would learn more if you visit youtube videos this is a good way to see how its done . You might just replace the front and rear with a pinchbar .But centre bearing will need the prop removed .So all the prop will need taking down to make all replacments easy . Important to mark all parts beforhand.Good luck .