I am getting my swap underway, using an 82 OM617.951, and I'd like to have a tach in the finished vehicle. I have the tach amp and signal wire with the engine, and the instrument cluster out of the dash. I intend to build a housing for the tach to put it in the dash of my truck, but what wires do I need? I see three heading out from the amp- Brown, that I assume is a ground, green with a black trace, and black. At the instrument cluster behind the tach there is a two pin plug with a green/black wire, and a black with a read trace. Is this the actual input for the tach?
I know there is a modern replacement for the amp (in the budget sometime in the spring), but has anyone made an amp that can work with a standard aftermarket tachometer? It'd be so nice to get one that matches the rest of my instrumentation without having to spend tons on a full VDO set. Plus, I don't really need a clock.

Yes, that's the plug from the amp to the tach, with the extra wire for power, can't help with colors other than the brown is ground.

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83 SD

84 CD