Yes that’s for the most part correct but I think the 85 gauge expects a different pulse frequency since it triggers multiple pulses per revolution unlike the pin on the harmonic balancer. I think if you do this you’ll also need a tach from an 82-83 turbodiesel with two pins rather than three.

I take it the pickup on the bell housing is gone? It may be easier to try to fix the 85 system rather than install an 82 system. Just a thought.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles