Ready to upgrade to a modern 4 speed electronic transmission but want to use your existing Mechanical speedometer? Now you can. With this conversion tail housing, we give you the option to have both the electronic speedometer output for your computer as well as a mechanical speedometer output for your standard GM mechanical speedometer cable. This kit only fits the '98 - up 6 bolt style tail housings, for 4L60E, 4L65E & 4l70E Transmissions. We must have your tire size and gear ratio.