I had noticed this with my own dad but hadn't made the connection that it was widespread, but I think you're on to something. Does it mean that now that I'm past 50, my group of friends will slowly reduce to 0 and then begin expanding again as enemies?

How many friends are necessary for a good life and how close (geographically) do they need to be? I had a good friend in college but hadn't seen her in 25 yrs. We hooked up in NYC a few years ago and it was as if no years had passed. Our friendship had been able to survive that long dormancy and despite all the things that had happened to us in the intervening years, they made no difference. Some of those changes were substantial. I had changed from being a minister to being a functional atheist while she had continued on in her role as a minister's wife. It makes me wonder what are the precise psychological/sociological grounds of friendship that seem to transcend apparently fundamental differences.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13