I have a 2002 Grand Caravan with AWD and 3.8L engine. I bought a tranny out of a 2004 Grand Caravan 3.8 AWD. Will it work?

Yes it would, they are both from the same body style.

+1 Master Tech

you may need to swap eletrical bits or swap plug ends as the factory liked to change plug designs from year to year on some components.
then again it all may just plug in.

it will be easy street