Certainly a few clues of an HG failure being mentioned 🤔

Its definitely not a vent it cap, so has been modified, looks like its a 20mm hole so per have they intended fitting a sensor. The vent to stop a vacuum will be either a 5mm hole on the side or the cap is manufactured to include a vent underneath the cap. A new cap will have the part number NTC2723

I assume the tailgate was functioning 100% before. So whoever did the work in replacing the tailgate would have left some pencil marks to aid realignment when fitting the replacement, something similar to bonnet and side doors removal and refitting, perhaps they didn’t… hence the tailgate is...

As already mentioned you will find the info in the owners handbook. Whit most modern cars theres two handbook, basic and the full on version which u have to download from LR via their app. Then look for the chapter ‘driving modes. Not a disco I know, but it may look like this, headings and...

SOLD. Sold it after 26.5 years of ownership, it was just a replacement for my rusty 10 year old car RR, I didn’t need the disco after the first 2 year, the job I had for it landscape my new garden was now finished, but kept the disco as it as it was relatively issue free, also the company cars...

Not normal D2 V8 UK spec engine then. Here in the U K we have a D2 with a Thor 3947 engine, which is so call by Land Rover a 4.0 litre D2, a different engine to D1 but the same CC as a D1 V8, which is called a 3.9. So where in the World are you?

I’m If you have grease in the steering swivels the you will have Teflon coated swivel balls, if the balls are chrome then they will have fill and drain plugs plus early swivels also had a level plug as fitted to my old RR 1987 so the oil could be replaced at the service interval. My 1997 D1...

Now corrected😊

My quick search gives me a LR part number as STC778 Kit headlamp cover so possibly nothing to do with adjustment, anyway unfortunately they are obsolete.

Wading plugs are only fitted on vehicles going into water that having a timing belt and/or a clutch, autos and/or a timing chain don’t need them.

I have explained what is dim-dip and how it functions already.

🤔 my 1987 RR wasn’t equipped with dim-dip nether was my TVR in 1985.

Yes, a resistor which is mounted at the rear of engine bay, just unplug it to remove the dim-dip function.

🤔 Pink relay ? No such thing fitted to a D1 and the only item that dips the headlights with the side lights on is the lighting switch. With D1s dim-dip feature, when the side lamps are switch on the headlight dip beam is then on but in a dim mode, when the lighting switch is turned to main beam...

All you will find regarding a heat shield under the vehicle it will be bolted to brackets below the floor and positioned above the mid exhaust box, although some times with after market mid boxes it attached. If with the D2 you need the heater dampers closed to stop the hot air flow into the...