AFR Gauge Question

[Donkeylips]

So Ive researched this and posted on other sites... I have installed an Air to Fuel Ratio Gauge in my truck. My is truck is a 94 Toyota P/U with the 22RE.The problem is: I don't know which wire on the O2 sensor to tap off of. If anyone has an idea please help. I also looked in my Haynes manual buy I could find anything.

Thanks in Advance,
Kurtis