Dick,
Only the 16 wheel and the 34 wheel monitors are capable of monitoring your tow vehicle and your 5th wheel or trailer. The only difference in those two is the face of the monitor, the number of tires they can monitor and the price. The 16 wheel monitor looks like a motorhome pulling a toad and sells for $190. The 34 wheel looks like a truck pulling a trailer and sells for $205. Either one of those monitors will work for you if you don't plan on towing a vehicle behind your 5th wheel. We tow a car behind our 5th wheel so the 34 wheel monitor is the best one for us.
If I can answer any questions, you can email me at:
sales@pressureprosystem.com or call me at 850-294-0281.
Safe Travels,
Pat