YES IT DOES WORK WITH EVERYTHING, your speedometer gear is on your transmission OUTPUT shaft. If it wasn't the speedometer would read wrong on every gear but high or overdrive. It monitors driveshaft RPM, not engine RPM. The engine rpm will rise and fall with the trans in different gears but the only thing that counts for speed is driveshaft rpm. Only two things will cause a varience, differant gearing or tire size change. Your driveshaft will turn faster or slower depending on the rear gear ratio so if you change it the speedo will read wrong. Same for rear tire HEIGTH, width means nothing. In other words the ONLY thing that counts is driveshaft RPM, the speedometer doesn't care if the driveshaft is being turned by a three on the tree or a double overdrive 6 speed Tremec.
