380 Amps of what?

You will need very large wire to the rear of the truck, a very large connector (like the Anderson pictured), and very large wires on the RV side to the batteries.
What batteries do you have? It it's a fairly normal sized bank of around 200 AH then most current you could reasonably hope to put into them is probably about a C/5 or 40 amps. If you assume the truck wiring is 25' and the RV wiring is 10' then you need wiring to carry 40 amps that distance with minimal voltage drop. By my calculations something around 250 MCM would give you just over 1% of voltage drop.
This size wire is huge for RV work. So, basically, the biggest wire you can manage to afford and install.

drittal wrote:

austingta wrote:
That is a funny notion...a government agency spec'ing a Denali ambulance!

A government agency spec'ing a Denali seems like a waste of tax payer money.

It's only tax dollars, there's plenty available. And, it's easy to raise more....:E

austingta wrote:
That is a funny notion...a government agency spec'ing a Denali ambulance!

A government agency spec'ing a Denali seems like a waste of tax payer money.

Ask this question again in the truck camper section. Many run a constant duty solenoid and heavier gauge wire to recharge their camper. The same is done in many Class B's. DB slipped in some photos before I finished responding.

I have dual alternators in my dually. No idea why the dealer ordered it that way.

I did some heavy duty charging upgrades to power my truck camper while driving:







Andersen connectors and 4AWG wiring.

In an RV application it would be next to impossible to utilize your full alternator output. If you had an extreme need, like to run your trailer's AC while on the road, you would want to direct-wire a large inverter (minimum 2000 watt 3000 surge) to your truck battery and run a 12 gauge minimum extension cord to your trailer. Otherwise I see no practical way to use that kind of capacity in your application.

That is a funny notion...a government agency spec'ing a Denali ambulance!

The dual alternator option is more directed towards up fitters for uses like ambulance etc...

To make use of that much amperage, which you will never do, you would need some serious wiring.

http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html