Yes, the top center hole is where the sending unit goes. I will install the tank so it can be "easily" dropped. There is nothing easy about it because the leaf springs get in the way of the tabs used to bolt the tank to the frame. But with that said, that is good advice. The filler hole is in the lower left corner of the photo. It sure would be nice if someone had a layout of where the center of the filler spout should be positioned from the center point of the frame. I think that location is 17 1/16" from the center of the frame. That should land the 3" diameter filler plug assembly exactly in the center of the second board from the left bed wall. But is sure would be nice if the tabs on the tank were slotted so you could make any slight adjustments (left or right) necessary to hit the location spot on.
