Odometer switch is at the lower left corner of the firewall on these cars, where the subframe goes under the firewall. Eqasier to reach from under the car. Look for a box with one speedometer cable running to the trans, another going up thru the firewall. It will also have one or two buttons. The buttons may even have their original protective covers. If it still has the cover, pop it off. Then press the button in with a screwdriver, because it goes down way past flush. Pop the cover back on to keep crud out.