1990 t-bird gauges

My gauges dont have a tach i was woundering if it interchangable with one with a tach.

Since no one has come forward with an answer and I don't know myself the best answer I can give you is to get a wiring diagram and check the pinout on the connectors of the two clusters themselves. See my post on the first page of the Tech help thread on where to buy or check your local library for a Mitchell electrical manual for your year car. Autozone has some diagrams on therir website but I don't know if they are detailed enough to answer your question. I do know that the connector pinouts were different for these two types of guage clusters in the 1979-80 Capri's so I wouldn't plug the tach cluster in without checking the connectors first.