You could ask the credit union what remains to pay on the vehicle, and offer that in exchange for the title. If they won't accept that, there's not much more to do, as the credit union's security interest is still valid, even though they can't go after you on it.
I would suggest contacting your bankruptcy attorney about helping you. It might cost you something, but there is no reason why you can't either get the title or turn the car over to them. I'm guessing the lender doesn't deal with a lot of bankruptcies.