How to Wire a Sunpro Tach | It Still Runs Sunpro is a maker of gauges and tachometers, and has been producing these devices since 1935. The tachometer grew in popularity in the 1960s and 1970s with the rise of sport and muscle cars. Tachometers are devices that measure the revolutions per minute (rpm) of the engine. This helps the driver monitor the vehicle MSD 6A and SunPro II Tach.. - forumsey Apr 04, 2008I've read a lot about the problems with tach compatibility and the MSD 6A ignition control box. Most postings don't address a troubleshoot that I understand so I'll give it a go with my own on this redundant issue. :confused1: My old SunPro Mini tach worked fine for several years attached to the tach output of the MSD box. A few months ago it started acting erratic, then it just stopped working.