How do you repair a ford 3.03 3 speed manual transmission stuck in first gear?

It's very simple, if you look under the hood near the steering column you will see two arms that travel down to the transmission. Wiggle the arms where they connect to the transmission until they unstick. You should have to get lay under the vehicle to get at them.

--- Just note that one lever must always be in the neutral, or center position, or the other lever will be locked up. When the linkage wears, the shifter often tries to throw one lever before the other is fully in the center position. This jams up the transmission and is the cause of your problem. As the guy above says, to unjam the 3.03, you have to get under the car and push one lever to the middle (neutral) position.

Then you're good to go.

Fix that linkage!