There are not so many recordings circulating from the US-Tour in 1980.
Unfortunately Richfield is on of those which haven't seen the light yet. But a recording of this show exists I was told.
I read about it's existance, too. I never came across a recording labeled as Detroit1980. But let's keep our eyes open.
I started to post requests in German newspapers for picture and sounddocuments of still missing German shows. Perhaps you could do the same in your home country, althought it's much bigger then mine.