Legal contract question

Hi all, and especially those with legal knowledge,

I am buying a new (used) car from a dealer. He doesn't want the car I have (a Griffith 500) in part ex but has agreed to try to sell it on my behalf. Has anyone got a draft contract (or ideas of what to put in a contract) to ensure that, whilst he will have my car in his possession, it remains mine until sold, and that the proceeds of the sale are mine except for any agreed fee?

Thanks.

R****f?