Not sure on the Equus tach. the only information I found on other sites was that they fit 4,6 and 8-cylinder engines. You could probably hook it up, but it would only show half the actual rpm. I haven’t installed one on my Hijet, just go by ear. Lots of folks have gone with the GlowShift successfully.
So, last night I discovered that Glow Shift has an outlet store on eBay where you can purchase used or refurbished GlowShif gauges. The seller name is: glowshift_outlet I was watching a 2-inch tach they had listed for $39.99, and just accepted their offer of $30. So, you can get them for a decent price. They only have a sixty day replacement warranty, and they have different conditions from like new to having visible scratches but functional. So, if you’re interested be sure to read the description.