I think you have a couple of options but the first one is probably quicker and should be less stressful.so now what? no warranty! trucks paid off . Im out of state working And have a rental uhal to tow my work trailer. I have a week to get home for christmas . should I get a new truck? buy new engine?
Option 1: Start with your insurance company. If the repair estimate is greater than 70% of the value of your truck, then it's totaled. That's part of what you have been paying for.
Option 2: Your insurance company should help with this one. Go after FCA to either get the engine replaced on their dime, or to give you the value towards a different truck.