So I discovered a small puddle of transmission fluid under the rear seal of my NP231, i checked the level and it was down quite a bit. I replaced that rear seal on the output shaft and the leak is still their, though it doesn't seem to be as bad.  Is their another spot i should be looking?  If so, what is the best way to go about doing this?  

How many miles are on the vehicle? I heard that on higher milage vehicles the seal can wear a grove in your driveshaft and that can cause a leak.  

you might be able to put a speedy sleeve on it and reseal it then there should be NO leaks.