If they total it, they will give you a low ball blue book offer. The offer is usually insulting. You do not have to accept the offer immediately. If you do not like the offer, call you insurance company and ask for their advice, and what they would offer in the same situation. Next, find prices on similar vehicles for sale in your area. When you call his insurance back, let them know that their offer is unacceptable for reasons X, Y, and Z. Give them the information you researched, and tell them you thing a more appropriate offer would be X amount. You can also negotiate to buy the truck back. Tell them you want X amount to total the truck, and you would like to buy the truck back for Y amount. Again, have your research ready.
In the end, you guys will either come to an agreement, or they will tell you to, "Take it or leave it." Then it turns into a legal battle, in which case you would have to determine if it's worth the time or money.