what transmission to use?

hello, I need some major advice! I have a crappy transmission in my 1993 sentra se-r. slips really bad, and overdrive is blown out. another words very crappy gas mileage... locally the only transmissions i can find are 5spds, but i dont want to do that swap. (it would be nice though:naughty: :evillol: :grinyes: ) but I found an auto tranny from a 1998 or 1999 sentra 2.0L my question is that will this work in my car? isnt that a 4 spd auto and mine is a 3spd auto? would i have to change the ecu? pretty much would it work and what would be involved in changing it? parts and what has to come off, etc..
thanks in advance

I'm pretty sure all SE-R's have a 4spd auto. Any auto tranny from any 2.0 should work. Try to get one from a B13 tho because I don't know if there are any mounting differences. See the Sentra README thread for models with the 2.0 motor.