Is the vehicle signed over to him? You have a few options. If the vehicle is signed over to the second owner on the back of the title, then a title needs to be placed into his name, then a new one into yours. If the vehicle has an "open" title, meaning the first owner signed it, but never put anyone's name on the back, then you could *possibly* put your name in the buyers position. It is also possible to contact the first owner of the car and have him obtain a duplicate title from his DMV and sign the car over to you.
Good luck, in any case it's a PITA.