[Shotimes] O2 Sensors

[Jonathon Beisler]

I am getting ready to replace the O2 sensors on my SHO.  I have two questions relating to this.  Firstly, do I have to have a special tool or will an appropriate size wrench work?  If so, what size?
Secondly, from where and how much should I expect to spend.  Napa stated that they were about 50 bucks and that you used the same type for each sensor.  Autozone, however stated that there where two different types of O2 sensors that needed to be used.  One "long" and one "short," whatever that means.  So,  what do I use?
Thanks, 
Jon B.