ka and sr are different. ka - distributor, sr - coil pack. i've never installed a tach on a sr, but usually you can do 1 of 3 things. either connect directly to the ecu tach wire (sometimes you get lucky and it works). connect to wire behind the gauge cluster (again luck). or you need to buy a tach adapter (autometer makes one, MOST COMMON WAY), so it reads the signal accurately. keep in mind every car is different.