which 3 wire O2 sensor ?

[Stowe, Ted-SEA]

hi, I want to slap an O2 sensor to my mg, it would appear I need to do this
at the bottom of the front pipe. while I found a one wire GM sensor, I am
dubious of it being hot enough all of the time.

there appear to be a wide range of prices for 3 wire sensors, (those with
heaters), can anyone suggest a GM oriented 3 wire sensor. (some of them are
quite pricey). 

thanks, Ted.