Freelander goes clunk clunk clunk!

Well I finally did it, I bought a Freelander to keep my olde Defender company!
Trouble is I bought one that goes clunk clunk clunk! I only paid £400 for it (98 XEDi) with six months tax and half a tank of the expensive stuff and three brand new tyres so I can spend out a bit on it, just a bit though!
I'm not Freelander savvy but have read up as much as I can and I will assume the VCU is knackered because the service history does not report it being replaced. So it makes horrible clunking noises driving slow in a straight line, goes a bit quiet when gently powering round a bend, still clunks like mad when coasting with clutch in. So I *assume* the IRD is knackered as well but I read the rear diff can also fail. What does mine sound like it has damaged?
I'm going to get it up on blocks soon and get the VCU off and hopefully check the diff, is checking the rear diff easy or do I need to take the plate off the back and look at the crownwheel? I know I have to check the VCU bearings (which seem tight) and the brackets that hold the diff but I think the clunking mine has indicates serious problems!
Finally, I know the Bell engineering bloke is on here but has anyone had any problems with their stuff? They look ok and I have emailed for a price new VCU and IRD but not as yet the rear diff!
I only drove the Freelander a couple of miles (gently) to get it home but I already know I like it, my land is VERY bumpy and the Freelander feels like a magic carpet on the rough stuff, better then my Defender as well.
Thanks for any advice!
Luggsey

Clonk could be the rear diff mounts. The one at the front often goes. Could also be the eggsause hitting the underneath too. You can have a go at checking yer vcu by doing the one wheel up test, as per the video below. Quick and easy to do.

Clunk,clunk,clunk sounds as though it might be a prop shaft frequency rather than diff bushes which are more likely to occur on drive take-up.
As you surmise the problem is your diff or IRD caused by over-stiff VCU. Doing th VCU test will show how stiff it is.
You can only see the diff gears by removing the rear cover. Dont take off the diff drive flange without reading Rave as you will need a new collapsible bush to refit it, as well as removing the drive shafts.
Draining the IRD oil and checking for debris might show if it is damaged. By removing the pinion housing you can see the condition of the bevel and pinion gears.

Anybody tell me why world of rover recon IRD's are only £469, are they any good?

has no one on here done a ird rebuild yet with the bearing kits?

I looked at doing it but after the cost of a rebuild kit it dosen't seem worth it...

Update: Drained IRD box oil and could see it was silver as it drained, loads of fine swarf on the drain plug magnet also, this I hope is 99% confirmation of the IRD being stuffed? I will be taking it out next weekend and then I will have a peek inside!
Took off the VCU/prop and have a replacement comming, I thought it wise to replace as it looks original. Now, I thought I would drain the rear diff to check the oil in there for signs of wear or damage, as already discussed here no drain plug fitted.... Is it a good idea at this stage to take the back plate off the diff? Any advice from others that have removed this is welcome as I don't know if there are problems doing it....Is a new gasket required or is it a metal/metal fit?
While up on the blocks and disabled so to speak I am doing a few service jobs, now where do I find the fuel sedimenter drain point or does my 98XEDI even have one? I looked in front of the right rear wheel arch but can't see anything like it? Any ideas??
Book says replace the Turbo boost control solenoid valve vent filter, what the heck is this and do I need to replace it? (90k miles)
Drained the coolant, flushed the rad, do I really need to flush the engine by taking the thermostat housing off? I filled the expansion bottle and that seemed to run through ok, I also filled the hose attached to the thermostat housing and water ran through there so I hope that's enough?
Finally, for now, There is a lot of oil comming out of the pipework above the turbo, some sort of breather pipe from the head goes to a plastic cased valve, around here somewhere oil is being released, what can I do to sort this out, new valve maybe?
Sorry for all the newbie stuff but I am a new Hippo owner!
BTW my local motor factors charged £10 a litre for the gearbox oil spec in the Haynes book, most I ever paid for any oil, the IRD oil was only £6 a litre......Hmmmm