I have had excellent results using the Scan Gauge. It simply plugs into the OBD port and mounting it on/in the dash is 5 minutes and couple of pieces of velcro. The Scan Gauge gives you so much data, trans fluid temp being number one on my list, and can display 4 different readouts simultaneously. You can scroll through a couple of dozen more depending on what you want to see.
The trans fluid temp readout is great to remind you to shift into Tow Haul mode (where you should be most of the time). This will often drop your trans fluid temp 12 to 15 degrees in just a few miles. Without the Scan Gauge you will not be aware of the increasing temperature which can easily lead to damage or a catastrophic failure.
In addition, the Scan Gauge functions as a built in code reader, very handy when your engine trips a trouble code. I initially installed it in my F-150 when I was towing our TT. When we upgraded to the Class C (6.8L v-10), I just reprogramed it for the larger engine and reinstalled it in the motorhome.
Last time I looked the Scan Gauge goes for around $140 - $150 on Amazon. I can't imagine running a truck or RV without one.
:C
