To accommodate the AWD there is a unique rear crossmember which is only found in the S40 and V50 Volvo's. Although the TE Kuga is AWD, the crossmember mounts approx 20mm rearward of the standard one and therefore doesn't center the wheel in the wheel arch. The other issue is that the Kuga one raises the car higher and the only way to bring it back down is with custom springs. This was the issue with the first cars Wolf in Germany did on their MK2 RS conversion. Don't bother with it, just find the Volvo one.
Comparison of rear crossmember - AWD top, XR5 bottom.
Everything will pretty much bolt to this AWD crossmember just the same as your standard crossmember. The only difference is the rear shock absorbers. Because they have to make their way around rear driveshafts they mount differently to an XR5 and are a unique length. For that reason you can't use whatever you have in your XR5 and will need to use the Volvo ones. Apart from standard Volvo units the only other options that I'm aware of are coilovers from either KW or BC Racing.
That's not such a bad thing as there is an important consideration regarding spring rates when going from FWD to AWD. In general most coilovers for a FWD XR5 will have the front spring rates approx twice that of the rears eg. fronts @ 7kg and rears at 4kg. With an AWD car you'll want those sprig rates to be close to or equal eg. 7kg front & rear. Given the limited choices I would opt for new coilovers to get the optimal spring rates.
If you're going this far then I would highly recommend doing adjustable camber and toe arms for the rear. This will allow you to get the best out of your coilover suspension and minimise tyre wear.
