Quite hypothetical really, as I don't own a Land Rover (yet!), but suppose I have a Series 3, 88" Station Wagon, complete with V5c.
1. I'd like to make it coil sprung, so I buy a brand new chassis. As its new, do I ask the DVLA for a new chassis number, or take the VIN plate off the old one and attach to the new one? Does it need IVA or will the act of showing 'new replacement chassis' receipt from manufacturer be enough? Straight swap = keep number plate, IVA for 'modified, coil-sprung' chassis = Q-plate? Coil-sprung axles required, so Defender/Discovery items fitted. IVA required as they're so different? Or included with 'new chassis'.
2. Having resolved that with the DVLA, I fit the SIII bodywork. It's all pretty standard stuff, just the odd 'slight' modification to fit the new bodywork or strengthen with chequer plate etc. No DVLA/IVA issues there. Same I guess for fitting winch etc.
3. Now to the running gear. I want a better engine, so fit a second-hand Izusu turbo-diesel. Not a major problem. Let the DVLA know it's number (stamped on block) and type, i.e. Diesel, turbocharged, and age of engine (from internet or manufacturers database) to allow for emissions testing. No IVA required?
4. New engine installed, but now, gearbox, transfer box etc need replacing, as they're not up to the torque of the new engine. So I buy a second-hand gearbox, from a Defender/Discovery. IVA again? It's permanent four wheel drive, but is this enough of a change to require IVA?
5. Lastly, power steering, for comfort and convenience. Again Defender/Discovery parts. Again, is this enough to need IVA?
Oh, and Hi. New member from Monmouth, South Wales. As stated, no Landie yet, but from the questions, I'm sure you can make out what sort of vehicle I'd like! I've no issue with doing an IVA, nor with emissions, I'd just prefer to avoid a Q-plate! Vanity I think.....