Been many a 6.5 that have died an untimely death due to balancer failure.

The serp pulley also has a rubber isolate'r that kills the belt vibrations common to the diesel.

The isolate'r has a bearing assembly and a metal spider to support the pulley, and when the rubber breaks its bond with the internal ring they hammer like crazy and will trash a crank in sort order.

I have seen balance'r rings get loose, IT AIN'T PRETTY

When it happens at freeway speed the driver usually needs a change of shorts

Good pix