Most facelift cars were H number plates and after, so this sounds a little strange. Also the face lift cars came with the common rail engine. People say all sorts of things about the diesel pump. But this 45k story applies to pre-facelift cars without the common rail engine. Then there's the belief that the common rail engine is good for only 100K miles!
Check the engine to see if it's common rail or not. The pre-face lift came with original 15" wheels and the face lift came with 16" due to larger front brake disks.
Considering the number plate is old I don't think even 5.5 is worth offering. Sri lankan market is such that, people will devalue this car due to the old plate and you will have a tough time selling it one day.