Fellas- I learned a lot doing this. You know the old saying, “experience is what you get right after you needed it” LOL.
So, got the Rivnuts and tool from McMaster Carr. One day delivery!. I had 3 bad Rivnuts on the main tank and one on the Aux tank. Both tanks were completely full. We used some hand tools to get the old/ damaged Rivnuts out. The tool is unreal, I will post part number in case anyone needs it. We put the new Rivnuts in, but had two that would still spin in the hole, couldn’t get the tightness we needed. Took them out and coated new ones with Locktite Red, then installed them and used the tool to knurl the Rivnut. Let them sit for a day then retightened. That was the ticket!
I believe all of this probably could have been avoided if I was more patient getting the old senders out. I had no idea they used Rivnuts and I was putting a little more ass into getting the screws out, which damaged the original Rivnuts. I even bent the tank lip some and we had to do some work to get that straight. It wasn’t perfect so we used some Gasoila E-Seal ( another freaking awesome product!) to put around the gasket. Took her out in some snotty stuff with the floor still off so we could eyeball the senders as we ran. Ran in some 2-3 tight chop with some 4footers mixed in looking for leaks but all is dry! Took me two weekends to get this back to normal, so take my word for it and be extra patient removing your old Senders!