Kathi-27, I have a question about your chosen sensor location. From your description, you have tanks with a similar profile to mine - a support ledge along the sides. If you install the sensors on the lower part, you must be showing full when they are actually only 50 - 60 %. Nearly half of my gray and black tanks is above the long side supports. There is also a step above the outlets so, that location is out. The only full depth side of the tanks is at the other end which is too close to a crossmember for the sensors, according to the instructions 2" minimum clearance from steel.
Anyone have any solution for this problem?