"Just bought a used V70 XC 1998. Noticed that the "cabin" creaks when torquing the body while driving over dips/etc. at an angle, like into the driveway. What might cause this? A problem or normal?"

This is a common problem. The 850/70-series were notorious for more than their fair share of squeaks and creaks, in particular from the dash.

Do a search on either of those terms -- squeaks or creaks -- and you'll find plenty of discussion of the issue. The search button is at the bottom of every forum page.

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Jim Rothe, '99 S70 T5M,
http://www.jimrothe.com/volvo/index.html