Well, ya need a a little over 16 quarts to fill the cooling system.
The FSM calls for the MOPAR Antifreeze/Coolant (Formula # MS-9769) due to the aluminum in the engine. The MS-9769 is a ethylene glycol base coolant with organic corrosion inhibitors (called HOAT - Hybrid Organic Additive Technology). They recommend a 50/50 mix of Ethylene Glycol and distilled water.
Also, do not mix your existing MOPAR coolant with any other type. Mixing of coolants other than the specified non-HOAT or HOAT coolant may result in engine damage due to corrosion.
So, if you can find some HOAT, 100% ethylene glycol and distilled water, you can mix your own. Or, just bite the bullet and go with the MOPAR coolant. I figure the coolant is cheaper than rebuilding or replacing the engine down the road.