down hill, so not accellerating, so wont be overfulling, as is occurring on overrun, compression test , stem seals, rings, or a blocked breather, so pulling in oil rather than air
pipe shrunk due to old age and hardening perhaps, blow through with an air line see if it will clear :)
otheriwise, 1 piece of trim removed at a time to locate :)
http://www.cws4x4.co.uk/discovery-breakers
http://www.carpartsnetwork.co.uk/Cars/Land-Rover/Discovery/5-Door-Station-Wagon/4.0-Metropolis/
there is a few arround :)
http://prntscr.com/ckj44o
looks like it's a drill job, as you can just make out the bolts going through the gutter here, there appears to be slots in the bar for the bolts to go through
http://prntscr.com/ckj4t8
highlighted in reg/green here http://prntscr.com/ckj61g
hope this helps :)
could...
pic of the bar, or link to the bar may help :) looking online at some, they fit as above by drilling gutter, another i've seen clamps on to the guttter without drilling :)
other option is gorilla glue, it's a foaming PU based glue moisture activated, and you can use a little at a time so dont need to waste a whole tin of expanding foam for a cpl of small holes :)
fuel lines can rub through, there has been a recall in the past for the issue
http://www.warrantyguide.co.uk/vehicle-recall-0A51A858052D41ED00256EA0002EA242-land-rover-discovery-series--diesel-
https://www.landyzone.co.uk/land-rover/leaking-diesel-around-fuel-tank.230168/#post-2643645
good...
http://www.ebay.co.uk/itm/LAND-ROVER-DISCOVERY-2-DEFENDER-TD5-GALVANIZED-CHASSIS-REBUILD-SERVICE-/151117547170?hash=item232f4ec6a2:g:q8oAAMXQt~hSK2cO
these may be worth contacting