If the buyer of the van you wish to sell cannot pay for it all at once and you are willing to allow installment payments for it over time, you need to do the following:1. draw up a written purchase contract to be signed by all naming you as an additional insured on the required policy of insurance by your state;2. draw up a promissory note for the amount to be carried by you with stated interest and payment dates to be signed by the buyer;3. draw up a security agreement to be signed by the buyer and recorded with your local department of motor vehicles;4. keep the pink slip for the vehicle in hand until you receive the final payment as stated in item number one (1) above.