Originally Posted by Moto Mel

You might get lucky if you change the fluid and bypass the radiator cooler as soon as possible.
You don't NEED the Jegs unit unless you are pulling a heavy trailer or in the mountains a lot. A standard H.D. unit that is available at most parts stores will do fine. You should seal the connections on the radiator because if fluid can get into the radiator you will likely lose coolant when the Nav needs it the most.
Good luck with it and let us know how it turns out.