Problem with a 96 Grand Caravan transmission.

I have a 96 Grand Caravan, and I've been having troubles with the transmission since I got it.

In the mornings, when the engine is cold, the reverse does not work.
The same with the first gear, but after warming up, it starts working.

Now the 3rd. gear is not working. I guess I need to replace it, but I wonder if I can use a 3.3 transmission??

Mine is a 3.8, 96

Thanks for your help...