The tach is marked as a Super Pro but it's an 8000 rpm tach to start with. The secret is refacing it to 6000 rpm while retaining the same 90 degree sweep. Then running the tach in 4 cylinder mode. I know it sounds weird but the math works out. I was just testing the accuracy against my laptop with OBDWiz and it works great. I think I bought the tach at Carquest but I cant be sure. Ive seen them labeled as other brands too. They're all the same tach except the gauge face is different.
Its the same tach as in
this article which was my inspiration, but I didn't really like the execution. I also didn't like the small resolution a 90 degree sweep 8000rpm tach gives. So I thought about it for a bit and realized I could reface it as a 6000 rpm tach and run it in 4 cylinder mode.
I'm not 100% satisfied with the first iteration of the tach so I'll probably make another one this week. I might do a small writeup showing all the things needed to convert the tach to a bolt in install too.