Check the listing for details. Marshall Tachometer Filter (9219). Condition: New. Listed at 36.95 USD. Tachometer Filter This compact, easy to install, tachometer filter is installed between the tachometer and the tachometer signal source (usually the coil). The filter eliminates signal noise and surges caused by many ignition systems. The filter modifies the sharp up-and-down spikes into a semi-square wave signal for steady pointer readings and faster pointer response. This tachometer filter can be used as a direct replacement for the original GM tachometer filter which is no longer available from GM (replacement for 1975-1989 Chevrolet Corvette tachometer filter, and many other 1975-1989 GM vehicles). Measures 2" wide x 0.75" high x 1" deep. Terms and Conditions Standard terms and conditions apply to this item. See our terms and conditions here: Terms & Conditions.