Does anyone have the Supra shop manuals? It will say in there what is exactly involved with the fuel level monitoring system, For all I know it could just be something on the fuel pump bracket, which would be pretty easy to access. Also, if you are worried about contaminating things, just do it when you have lower fuel, wear rubber gloves, don't leave things exposed for extended periods of time, and fill it back up before you start the car...if it's something easy to access like on the fuel pump bracket, then it shouldn't be too much of a concern of keeping things from getting contaminated.