buy a diesel car and convert it to run on used vegetable oil

I am very excited about converting a diesel car to run on used vegetable oil. I have a very talented neighbor who is willing to do this for me for very little money; however, I cannot find a used diesel Golf anywhere. I want a Volkswagen manufactured before direct fuel injection became a feature in the early 1990s. If anyone has a lead on a car like this, please let me know. I live in MD and my phone number is 949-633-3660 (cell). I would appreciate your help.

Thank you,

Lisa