Qustion Dr. D

I am goign to change my Crankshaft Balancer on Monday.
I am changing this as a preventative meaasure.

How come you changed the BOLT. do I need to change mine as well.

Also, do I need to lookout for anything different. Also, changing the Motor mount L R.
I want to make sure this mechanic does it right on these 3 items.

Thanks