speedo gear is pretty simple. take the bolt and clamp off that holds the cable into the tranny case. theres a clip that holds the gear on the cable , use a set of needlenose pliers or a flat-tip screwdriver, pull the clip, pull the gear and install the new gear w/clip and bolt cable back up to tranny case.
It'll probably take longer to get the car up on jack stands than swap the gear. Not really, but it's quite easy. Just follow 89streetbeast's instructions, shouldn't take more than 5 min once the car's up in the air, 10 max.