The problem with the common rail engines is the ammount of power they produce compared with the earlier ones, this has tended to make less unreliable if they are driven hard. The old TDS engine was less powerful but more reliable and much cheaper to repair. The last TDS's were sold in about 2002, they are only about 160 bhp which is quite enough to pull a caravan, the economy is not quite as good but that could well be compensated for by lower maintenance costs.