I think it is highly unlikely anyone has done this swap. It is likely you will have to be the guinea pig on this one. Maybe check if you can return it first if it does not fit. Wiring may be different and even the plug connector. You may be able to de-pin the 08 connector and fir the 07, but that al...

Have you checked eBay?

If you are talking about the p3 platform then the wiring appears to be very different. https://charm.li/Volvo/2007/XC70%20L5-2.5L%20Turbo%20VIN%2059%20B5254T2/Repair%20and%20Diagnosis/Diagrams/Electrical%20Diagrams/Mirrors/System%20Diagram/ https://charm.li/Volvo/2007/XC70%20L5-2.5L%20Turbo%20VIN%20...

They actually might be. The links i posted do mention the xc90 in them. i would check deeper to see if connectors match and mounting holes.