Deniss,

Vacuum leaks have no effect on a Diesel engine because the intake air is not throttled like it is a gasoline engine.

Things like the back up lights and door locks that U know about should be fixed before U buy the car because it won't be fixed by seller once he has your money.

Ball joints can be difficult to repair and U might need a special spring compressor. But the ball joints have a very long life, especially if U grease them with a hypodermic type needle like I do.

P E H