You first need to find out what would really happen if you ask the bank to repossess the truck. I doubt that they would simply accept the truck as payment of the loan. More likely is that they would sell the truck very cheaply at some bulk vehicle auction, subtract from the proceeds any costs associated with repossessing the truck, transportation, storage, cleaning/refurbishing, etc. Then they could still come after you for the remaining balance of the loan minus whatever might be left of the auction proceeds.

Worst case, the bank may end up claiming you still owe almost as much as you do now - but you wouldn't have the truck. If at all possible, sell it privately for the highest price you can get (do any needed cleanup and repairs yourself) and come up with sufficient funds to pay off the loan.