I dont think that you can swap titles on the loan. You will probably have to get a new loan putting the Del Sol up for collateral and using the money to pay off you Lude. However they are only going to give you the amount equal to the trade in value of the del sol. So if you are dead set on this trade you need to see how much they will loan on the Del Sol and ask for the difference between that and the payoff of your Lude.