Taurus tranny replacement...which one?

I'm replacing a transmission in a 99 Taurus Wagon for my Father in Law. The tranny is out, and I have a selection to choose from for the new one. The one that was in the car said AXOD on the pan, which leads me to believe it has already been replaced once, because it should be AX4S (as far as my research tells me).

So I have:
AX0D
AX4S
AX4N
to choose from. I know the AXOD are crap, so my real question, will the AX4N work in this car (which is most reliable) or am I forced to use the AX4S?

I would replace it with the same as removed, it'll be on the sticker on the door jamb as to the original trans,,, I would think, I could be wrong, that the factory trans is mated to your pcm program, swapping it out might cause issues, same as swapping engines may cause issues... a rebuilt ax4s will have the latest upgrades and should be pretty reliable, mine shifts and performs beautifully.. my son's 93 taurus with ax4s has 140k with original trans, only changed fluid and the mlps,, must have been the only good one

Yeah, they weren't entirely sure what to call them. After 1996, AXOD = AXODE = AX4S. You want to get AX4S

Nice. Thanks guys.

I was hoping that the AX4N would work. From my research, it's apparently the most reliable one.