I suspect what I’m about to ask is in now way a new question to this forum, so apologies in advance.

Looking for some advice. I have a low mileage 2004 2.5T SE which I bought cheaply as a stop-gap and two years on..... I love this car and cannot part with it.

Recently I decided to play with some performance mods and have already upgraded the exhaust and had a re-map done professionally to get a little more out of it. Very pleased with the results, and boy does it sound good. Next stage is an upgrade to a hybrid turbo, with injectors to follow, improvements to cooling etc.

The problem that I have is the gearbox. It is Geartronic so inevitably I'm losing a boot-load of power between engine and wheels and I've already had to fettle a flaring issue (usual problem with duff solenoids), but it is still not quite right. Looking at a manual conversion, so on the hunt for a lower mileage donor car that will allow me (actually my mate at AR Tuning) to swap all the bits across inexpensively. Trouble is that the 2.5 with a manual box is a rare animal and the few that are about are going up in price (most of them are also far too nice to break up).

From some scratching about on the internet it seems like the M56 gearbox might be a good option. I believe it was fitted as standard to the 2521cc S60, but i know little about it. What I'm wondering is whether and M56 from the more common 1984cc is an option. Would this be a straight swap into my 2.5? I know nothing about any differences in ratio, I'm guessing the bell housing will be different and not sure how many parts would be reusable in the swap. If the answer is 'not many' then it's not worth considering....

Apologies if I sound like a muppet here, I'm in uncharted territory and learning as I go. Any advice would be very gratefully received!