There is a higher probability that the speedometer board will be bad before the speed sensor and the most frequent problems effecting the speedometers are in the 90 and 91 gauge clusters. Yes you can use either cluster for auto or 5spd but finding a suitable replacement will be difficult. They are getting harder to find and people on places like ebay who say it will work for what you need really have no idea. There are many different variations. If you'd like to have it rebuilt send me an email at "techno at comcast dot net".