Been available for a couple of years. There's a group at Yahoo devoted to them. Lots of info there. I believe there has been a discussion of that failure mode. I think there should be a forum here devoted just to them.
Fedex and UPS use a lot of them. They were reviewed on Motorweek this week. They gave inaccurate mileage figues. They said 30mpg. The truth is around 22mpg. (They were probably using imperial gallon figures)

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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