What documents do I need to sell my vehicle with a lien on it?

The buyer wants a document to confirm that he will be the owner. As soon as the buyer pays for our vehicle, we will pay off our lien and the title will be sent to us. Is there any documents that can hold up in court so he knows we won't take the vehicle back and say it was stolen when the title arrives? Our title is in Tennessee and the buyer is in Texas, which where we are residing right now. Tx doesn't reconize a notorized bill of sale anymore so are there any more documents that will transfer ownership to him before the title arrives? Pleas help we need to sell our truck fast!!!