I used Rain X before, and TBH i found it quite smeary, though that could be down to user error not letting it dry properly, or pants wipers. Used it on the rear windows, which worked quite well though
All that really seems to leak on a TD5 (engine wise) is the r/c gasket or fuel pressure regulator. Saying that though, the oil filter has a nasty habit of working its way loose, so would double check that also
D3 IHU, as in Disco 3 Int. Head Unit?
Best bet is to ask on Disco3.co.uk, loads of people on there know how how to do it, and more besides
If were not talking about a Disco 3, then ignore the above
IIRC, door trim needs to come off the access the multiplugs for it. Once that is off, its reasonably straight forward though... Not much holding it on, but a bit of brute force is required to get the trim off. Bit scary the first time you do it
Or, if you wanted a 'spare' set for off roading only, I am breaking my freelander, with a set of 15" alloys. Found a fair selection of off road tyres for that size, and usually reasonably priced, if you are interested
I thought that having the shoes/drum would have had a bigger surface area, and would have been better? And how long is it gonna take for that disc to get all corroded and rusty!?