Hi all, this is my first post here so please me gentle with me

I'm in the UK where fuel prices are high and, as a consequence, the majority of Allroads are diesels. That's no problem as I like the bottom-end torque from diesels, much preferring them to 'cammy' petrol engines. I also like power though, so it's likely that I'll chip whatever I buy (easy increase from 180bhp to 230bhp) and maybe fit a bigger/second intercooler too if the design allows.

But that's later, first I need to buy myself an Allroad.

On average I cover around 30,000 miles every year, so I'll be looking to buy a car with 60k-100k miles on it and keep it until it starts to become a problem (around 200k based on what I have read?). Most of my miles are easy motorway, but I also do some towing (sometimes heavy) and the odd-bit off-road (I used to run a Land Rover with ARB air-lockers etc., so don't just mean a grassy car-park).

One thing I definitely want on my Allroad is the optional-extra low-range gearbox that was apparently available only on the manual models, but seemingly not on the tiptronic (why not? automatics can work brilliantly off-road)! In that respect my decision is made ...I'll be buying a manual car.

The problem though, is what year?

From various forums and reviews it appears that the early (2000-2002) 2.5 Tdi engines had problems with camshaft design in that either the lobes were pressed onto hollow shafts (and can ultimately slip and thus wreck the engine) or the cast ones suffer horrible wear (up to 1.5mm wear off the lobes) due to not being properly manufactured in the first place.

Seemingly the 2.5Tdi engine build quality improved in 2003 when Audi introduced a better material for the camshafts, so on the face of it that's the model year to go for. However, it's also the year when a lower-powered (160bhp) 2.5 diesel was introduced to run alongside the by-now 'standard' 180bhp 2.5 diesel, and all of the lower-powered ones were manual...

I definitely want a 180bhp engine, so how can I tell them apart (preferably remotely to avoid wasted trips to view)?

With that hopefully sorted my only problem remains the optional low-ratio gearbox which, according to this site - http://www.parkers.co.uk/cars/equipm...px?deriv=19029 - ceased to be available in October 2001! However, there's a lot of other stuff on that site that appears wrong, so...

Can anybody confirm whether the low-ratio gearbox was still available in 2003, or later?

If not, is it possible to buy a used low-ratio gearbox and retro-fit it to a later car that left the factory without one, or are there fundamental differences in e.g. wiring loom, gearbox casing, cross-members or mounts that make this a bad idea?

I'm mechanically able, having built and run various rally-cars and 4x4 racers over the years, and fully prepared to have to fix problems with the air-suspension shortly after purchase if necessary! I do the vast majority of work on my cars myself, but would prefer to avoid a complete engine rebuild if possible.

Any and all advice would be appreciated.

Thanks in advance,

Andrew