Hi Dave,
Yours looks like an original Sierra sender. I’ve just changed mine as it was leaking fuel from the uptake pipe braze. However, I agree with The District Sec - if you can , leave it well alone. It is very hard to reseal. I managed eventually by using a manufactured steel ring over all x4 bolts to apply a more even pressure to the gasket.
Try recalibrating your gauge with a Spyider module ? You wouldn’t need to remove the sender.