The Getrag built M66 gearbox is a very well made unit that rarely fails. It comes in two variants (FWD and AWD), three ratio sets (close, wide and diesel) and two final drive ratios. Volvo used this box extensively across just about every model from the small P1 platform like the S40 to the larger XC90 P2 platforms and mated it to their T5 and D5 engines. Ford used both variants but only two ratio sets in the Focus XR5/ST225, Mondeo XR5 and MK2 RS models.
The difference between the FWD and AWD gearboxes lies in the bellhousing and differential, as with AWD you need to be able to bolt a transfer case to it plus take the drive from the gearbox to the transfer case (using a drive collar). You can see the differences in the two pics below. The first is a FWD box and the second and AWD. Note the extra bolt holes in the AWD bellhousing and the larger seal opening to take the drive collar.
XR5 FWD Gearbox
AWD Gearbox
For Oz the availability of the M66 AWD gearbox is pretty grim. The only T5 manual Volvo cars we got were the 2004-2006 S60R (70 in total of which there are only 26 manuals, and you need to change the shifter mechanism), and the S40/V50 T5 AWD units (both of which are extremely scarce). There is one other source and that is the MK2 RS. Even though this is a FWD car Ford used the AWD gearbox for this application. That's great if you have an RS and want to do the AWD conversion but as there are only 314 cars getting a gearbox from one is nearly impossible. In UK/Europe manual T5/D5 Volvo's are much more common and there are more options for finding a gearbox but then you have to freight it out etc so it won't be cheap.
The key to any MK2 Focus AWD conversion starts with finding a gearbox. To add to that you need the RHS driveshaft which has to be from a manual. The auto driveshafts are approx. 15mm too short and don't engage with the internal spline of the diff in the gearbox. It's important to note that all the Volvo M66C boxes run 26 spline driveshafts (same as XR5/ST225) but the RS box runs 28 spline which adds additional complexity and will be discussed separately.
There are three ratio sets - close (RS/XR5/S60R), wide (S40/V50/Mondeo) and long (Diesel Volvo's across all models). The ratios are listed in the table below.
