If you are serious about your driving then you want to understand how your engine is responding to your urges. Many types of tachs are available in the aftermarket but since we drive British it should say "Smith's"! Available in either 8,000 (RVC1006) or 10,000 RPM (RVC1004) version, the classic looking 3" diameter tach has a chrome bezel and red shift pointer. Suitable for negative earth only.
If the manufacturers part number has a CA suffix it can be used for positive or negative earth