D3 A8 V8 engine swap?

[ontheball247]

Hi guys. I have a 2003 A8 with the 3.7L engine and GQE gearbox. Now the gearbox is troubling me (I have another thread on this) and I've been offered the 4.2 engine and gearbox for quite cheap. I've been searching but it seems no one else had done this.
Firstly what parts would i need in order to do this swap other than engine and gearbox? (For a start, the guy selling it suggests i won't need the ECU which seems odd to me. He says i just need the wiring loom and i can plug that into my existing ecu. If that's somehow correct, i would prefer this). From initial thoughts, would i need the keys and ignition system from that car? And are the radiator and cooling system, brakes, suspension, etc. All the same? And the main drive shaft, diffs, etc. (My car is a Quattro, so that might be something to bare in mind).
And secondly what would i be getting into with the swap?
Thanks in advance.

[EG-4.0TDI]

Interesting project! All the 4.2s were Quattro so that aspect shouldn't be an issue per se...

I would think that the short answer to 'what am I getting into with the swap' is: 'A shed load of labour'! I'm not knowledgeable on the technical aspects as to what can be plug-and-play so I can't really help from that side. I know that there are all sorts of component protection issues on mundane things (like bits of the sat nav) which can require re-coding with a connection to Audi central so I would imagine that getting all the bits to talk to each other and play nicely after the installation might be quite involved.

More helpfully, perhaps, I can tell you that an engine drop is about 30 hours of book time because it requires the removal of pretty much everything you can imagine from the rear diff forwards. The engine drops downwards (rather than lifting out upwards) so you need a pillar lift and an engine bed that is chunky enough to take the weight. When my 4.0tdi was dropped, the main dealer had to borrow an engine bed from a Bently garage because the common-or-garden kit couldn't take the weight!

[ontheball247]

Thanks I'm glad you think so....the idea intrigued me when I first had it. When my gearbox got worse I started thinking of options...one being to count my losses, strip this for parts and get what i can and look for a good 4.2 (which I should have done in the first place), and the other to put approx 3k into this gearbox for a full overhaul...Nope!
Just out of curiosity I started looking up A8's breaking for spares and got a reasonable price for the 4.2 plus gearbox. But even as cheap as the engine and gearbox are, I think the labour cost alone would outdo the benefits. With 30 hours into it, and that's even before I've considered all the extra parts I'll need (at the very least I'd do the timing belt, pulleys, timing chain guides, water pump and thermostat on the replacement engine before it goes in, and then there's the possibilities of what I'll need for the electrics and communications, as you've mentioned), I don't have much hope here. lol....Anyway, many thanks for the input. And if anyone else has any more to help with this, please share....otherwise 3.7 V8 engine anyone? Just shy of 100k and full service history with recent major service :)