I have a set of Atena Engineering Tachs that I took off my boat when we repowered it. I had Detriot 6v-92's and these worked great. Only used about 2 years before the repower. $300.00 for the set. List for $296.00 ea. Here is a link about them http://www.aetnaengineering.com/wp-content/uploads/2016/01/8905-LCD-Tachometer.pdf I can send pictures if interested.