1988 Chevy S-10 spedomoter cable

Remove the old speedometer cable from your car by first taking off the doghouse and the engine cover.
Locate and remove the bolt below the dashboard and let down the steering column. Doing so will allow you to get to the back of your speedometer.
Take off the drive shaft nut and the "O" ring and drive the speedometer cable through the firewall.
Get rid of the clamp securing the speedometer cable (located in the engine compartment) and the clamp holding the cable in place (found on the transmission.)
Release the drive shaft nut from the "right angle" adapter. The nut is attached to the rear of the transfer case.

Replace the Speedometer Cable

Place the square end of the new speedometer cable into the adapter and secure the drive shaft nut.
Pull the speedometer cable through the firewall to the rear of the speedometer.
Secure the "O" ring and attach the speedometer cable to the rear of the speedometer/odometer. It should be engaged in the speedometer's square hold. Tighten the drive shaft nut again.
Replace the clamps that will secure the speedometer cable onto the transmission and in the engine compartment. Replace the engine cover.
Drive your car slowly to be sure your speedometer is working properly. If it is, replace the doghouse. If you're stilling having problems, take the car to your mechanic.