My advice for what it's worth.
1. Get price on exchange gear box local garage.
2. Check all MOT's look at mileage.
3. Has it been serviced at all any service history?
4. What's coming out exhaust? Black smoke/white smoke.
5. Diesel emmiting black I'm told is worn injectors not cheap to replace. Not sure but white could be oil and you can smell it. Open oil filler cap when engine running see if smoke comes out or sludge around filler tube.
6. Whining could be alternator power stearing ???? guessing...
Think about it look at others then decide it's better to miss it and end up with something else than buying trouble.
Charlie
May 2009