I have just bought a cheap Freelander for spares as the IRD was on it's way out due to the visco that was past it's sell by date. I have taken the rear prop shafts and visco off (Mondo Mode) and she drives well with no noises.I have un screwed the IRD filler cap and the cog behind looks good.
The car is far to good to scrap, what are the chances of the IRD lasting in mondo mode ?

The cog behind the filler doesn't normally wear. Most problems are between the pinion and large cog it connects to. One or the other lose teeth and it forces them apart, which cracks the case. Yer can be lucky and get funny noises before this happens. Bearings can fail anorl. If you undo the ird drain plug it has a magnet on it. This will collect metal bits. A little bit on ere is normal. Loads is a problem. Always undo the filler plug before the drain plug, as many have struggled to get the filler undone as it's a soft nut (crap).

If it's running ok then it probably is ok. If bearings/gears are damaged then there's no magic fix other than physically changing parts. Removing the pinion to look at the larger gear will tell you if it's damaged, if yer really want to know.

Some info: https://www.landyzone.co.uk/land-rover/cracked-freelander-1-ird.278571/

Thanks Hippo ! Top man ;-) Was thinking of whipping the pinion off and having a look anyway ! Not dropped the oil yet so I don't know what that's like !

Give it an oil change and look at the drain plug for bits then. Don't ferget to undo the filler plug first. this will give you an idea of it's health normally. Have a look at the filler plug before just in case it's already rounded oft and yer need a new one. Knocking the bucket of oil over is optional.

You can get a pinion blanking plate, saves having meshing gears if things are awry.

Cheers chaps ! yeh them there IRD drain plugs are a reight bastid to undo but have already managed the it !!

I drained the oil and took the rear prop drive flange out and although the drive flange looks to have wear non of the teeth are missing. Bit's of what looks like the bearing flange cage were in the oil !Having made a plate for the flange hole (sounds nice) in the IRD I would like to change the flange bearings but having got the nut off can't seperate the shaft !! Probably need a press eh !