trans question

I have a 1989 grand prix. The trans went out on it, 4 speed trans. I picked up a used one that was supposed to be a 4 speed, but is one wire short on the connector which is for the 4 speed, Will I be able tu use this trans and just have a three speed, if so, will the pcm need to be reprogrammed? or am I screwed?

Please help

some one must know if a non overdrive trans will work in a car that had overdrive and what needs to be done to make it work