Someone just posted a thread about retrofitting this to their W124. It didn't seem that bad, but did require a donor car at the junkyard.

The brake interlock won't let you shift out of Park unless the key is on and your foot is on the brake.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.