All the P2 manual M66's will have the same mechanism, petrol or diesel won't matter or you can make your own and shorten up the shift from odds to evens. Modifying the XR5 cable ball end to take the 850 cable makes the cross gate narrow but it feels nice. It would be possible to increase the height of the cross gate mechanism to widen it if preferred.
Nothing inside the car was changed and original 850 cables are used.

I cut up the M56 cable mounts and cut off the XR5 cross gate mount (left hole) and welded the M56 in the exact same spot. It would be possible to grind out the hole to suit the 850 cable but this was quicker. The throw cable mount was then welded after centering the shifter inside the car. I'll compare it to the S60R cable bracket but the gearbox will come with one so no need to buy an extra part.
The thermostat on the airbox had to be removed as the S60R mechanism hits it but it still just touches the underneath side of the airbox. I plan on making my own short shifter so it won't be an issue.
Ask for the clutch line to be included with the gearbox you buy as you'll need it to modify the original M56 one to work.