I have a 95 Z34 and I'm trying to replace the O2 sensor that is before the catalytic converter. It seems like a really tight squeeze so does anyone have any advice on expediting the process? Also, I am trying to find underdrive pulleys, specifically the crank pulley since in my experiences with other cars that is the one that adds the most power and the other pulleys usually shorten the life of what they are on such as alternator, water pump, etc. Does anyone know where I can find one, or at least if there is another GM engine that uses the same pulley?