I'd wager a guess that the dust shields don't need to be changed. If they are different, then the flange of the original smaller shields can probably be bent/cut back to clear.

This is probably a good time to check the parts catalogs. Compare the brake parts for your V70 vs those for a V70R. I presume that's what you're after. Also you can do some searching for "big brake kits" (BBK) on the Volvo classifieds groups. I'm a member of one group on Facebook where there's usually someone who's selling some R brakes.

All that said, I, like the others, don't have direct experience with the swap and am of the opinion that the stock brakes, with good pads and rotors (fresh brake fluid will help too), will be adequate for whatever towing you should be doing.

Best of luck,
Will
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XC60 / Odyssey