I just spoke to one of the MB dealers here in san antonio and they said they only have resistor type plugs for my car but my car calls for non resistor plugs. An 86 420sel. Whats the dealio?

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual