3 speed to 4 speed

If your talking pre O.D. trans, yes. Providing your bellhousing has the extra threaded hole on the bottom right. The bottom right ear on the 4 spd is kicked out more than the 3 spd. You can see this unused hole with the 3 spd bolted in. I'm assuming since you have a floor shifted 3 spd you don't have the light duty one with the cover on top.