Need help with speed sensor

I pulled a code for my 94 Honda Accord EX AT for a bad speed sensor. Car shows the symptoms of a bad one. Can anyone lead me to a guide for replacing this and also give me the name it's called when you go to all those Honda parts sites? I have a copy of the 94 Honda service manual but can't find the page for this.

Also, is it fine to use an aftermarket or does it really make a difference with OEM? I've heard the OEM part is $130+ while aftermarkets are under $30.