Did the owner simply give up on the car? Any shop can drain the tank.

Hypothetically you'd prefer that the tank was empty, filled with gasoline and the engine died within a block or two. If the tank still had a fair amount of Diesel, it might have run longer on diluted fuel leading to more severe damage.

Bring a gallon of Diesel, some fuel line and a new spin-on filter - heck even an old spin-on filter. Fill the filter with Diesel and install. Have the lift pump draw directly from the gallon container while you attempt to start the engine. If the engine runs smoothly after self-bleeding, I'd say you have a winner. Have the car towed to a shop that will drain the tank.

Sixto
87 300D^2