4 cyl. tach conversion

Not an A body, but I've been converting the gauge panel from an '88 Daytona to fit my '88 Dakota- full gauge instrumentation as opposed to the Dak's idiot lights, buzzers and blank spaces. The gauges and speedometer present no problems, but I also want to use the tach. I remember there being a particular resistor rating to run in the signal wire to make the tach read V8 rpms instead of 4 cyl., but I'm having issues finding the value needed (Google hasn't been any help, either). I know I could just wire in a potentiometer in the 1K range and adjust it using a hand held tach, but it'd be nice to just solder in a resistor and be done. Does anyone recall what the value is?