@Nodge68 I'm gutted for you with all the problems this vehicle is giving you, and I understand your concern about the vehicle. It has indeed been something of a problem child, and would appear to be a bad example / unlucky motor. And as such I can understand why you are thinking on getting shot of it, as I see it you've got five options:
- Do the diff then preemptively attack other weak-spots giving you a reliable motor for the future, or do the diff and jog it on. What would be next, as in what are the other known potential failures? Haldex unit? PTU? Gearbox oil change? Caliper refurb?
- Whack in a diff and lob it on gumtree / eBay / Autotrader
- Sell it as is "for spares or repairs"
- Break it
- Torch it and claim the insurance
They are all options, but big decisions, Were I going to jog it on I'd be fitting the cheapest diff I could get my hands on, were I keeping it, I'd rebuild the diff or get onto someone like Bell Engineering. I personally wouldn't consider pursuing options 3, 4 or 5, but I've presented them as things for you to consider. Perhaps you might be served well by doing an assessment of the motor overall, run the oil out the other three transmission components (gearbox, PTU & haldex) and check them out as best you can maybe with an endoscope (£10 ebay USB gadget or I could lend you either or both of mine) and decide if they are ticking timebombs or are they in better condition than the other systems you've been dealing with thus far? That would give you some information on where you stand with the vehicle, and what you've got to work with on it.