The 1xx chassis is an electrical dream to work on. Except for some bad choices in wire strand counts across hinges, the wires are nice and solid. You can actually maintain the connectors or worst case rebuild the harness with a soldering iron. Or you can do neat tricks like convert from a 4-pin to 5-pin OAT display without having to cut or splice any wiring.

You can actually still buy the housings and the pins and sockets.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech