rado ON A SIDE NOTE IV'E GOT THIS ON THE RADAR
https://www.speedingparts.eu/p/brake-system/brake-caliper-adapter/s60rv70r-rear-volvo-850v70i-brake-caliper-adapter.html
Finding the P2-R rear calipers is the issue.
I trolled the sites that sell new or refurbed calipers for Brembo as OEM for Mercedes and others not labelled as Brembo. You may find them in a Mercedes junk yard!