The gmt800 flex fuel vehicles use a very expensive sensor, $400+ iirc....the tables may be in the non flex fuel vehicles just not enable. Some of those engines came with rediculously small injectors 24lb/28lb injectors will not flow enough e85 to keep up. For gmt900 the factory uses a virtual sensor, which is just the o2 sensors monitoring outgoing exhaust and fuel trims to determine E-content, it's not that great. Gmt900 the sensor is pretty cheap 50-75 depending on which you get, however you need some fittings to put it in the fuel line. I grabbed a sensor and quick disconnect fitting but it's to long to all go inline, so I need to grab some more plumbing to make it work. This probably what I'll end up buying: https://dsxtuning.com/collections/f...sx-flex-fuel-kit-for-2006-2009-trailblazer-ss Is gives you a y-adapter for power and you need to install a pin in the ecm And @LanceD how'd your e85 adventure go?