Cummins has released a new connecting rod for its ISX engines.
Connecting rod 4059429 replaces connecting rod 4923749.
The new drilled connecting rod represents a change in design and a departure from the “non-drilled” connecting rods commonly found in the ISX units.
For further clarification on connecting rod changes on ISX engines look at Cummins Reference TSB100666. Newer ISX engines (starting with ESN 79614966) were built with fractured rods. Saw cut and fractured rods can be mixed in an engine per Cummins Engine Company TSB120067.