Rivetting Fuel Sender?

[snapper]

They'll spin when you come to take them off.
Riv nuts work well
As tanks are either thin steel or thin soft ally a load spreading collar on top of the sender spreads the clamping force evenly.
Sealant is not usually needed but if you do it has to be petrol resistant.
Sikaflex or Tigerseal is not and will drop into your tank and block up pipes, filters and pumps.
Gues how I know that?