Factory gauges with a LS swap.

[CarlC]

If you want to keep the stock look of the speedometer, IMO, the best way to do it is to have the gauge reworked to accept signals from the ECM.



Here's mine reworked by Redline Gaugeworks. I had them add a Check Engine light as well. They also reworked the tachometer. Both work perfectly, unlike some of the cable-driven options out there.