A monitor solution will be your best investment. Knowing what is happening with your motor temps/psi/volts will give you a heads up to prevent expensive repairs.
You have choices here, the Edge Insight CS/CTS with expandable cable will allow you to monitor the motor thru the OBDII, the expandable cable will let you add sensors like EGT and Fuel psi to be read on the monitor.
The ScangaugeII will monitor thru the OBDII ports, but has no external input for EGT and Fuel psi, so you will need separate analog gauges for EGT and fuel psi.
If you have a Android smart phone, then you can use the "Torque app" and a OBDII Bluetooth module to monitor the engine, but you will need separate analog gauges for EGT and fuel psi.
If you have a iOS device (iPhone/iTouch/iPad), then you can use DashBoss. It's a OBDII plug in to monitor the engine on the iOS device, and has external plug to add EGT and fuel psi to be viewed right on the iOS device.
When your ECT/EOT delta gets more than 15*, it's a good chance that your oil cooler is getting or has clogged and may cause a chain reaction to cause the EGR cooler to fail and possibly cause headgasket/bolt failure.
Low FICM volts and/or weak batteries can cause damage to the injector.
Low fuel psi, can also destroy injectors.
Here is some reading material.
Things to consider about owning a 6.0L
Write Up: Bullet-Proofing the 6.0L PSD.