Installing new fuel tank sending unit ?

[Mountain Man]

I have a new fuel tank sending unit on order , so my gas guage will finally work. Tired of topping it up all the time, because I am afraid of running out.

Does any one have any advise on the best way to remove the ring that holds it in place ( this is the in cab tank).

Would it be o.k. to switch it out with the tank half full. Don't really want to pump it out, and will not likely be driving the truck much in the next few weeks.

It does not look that difficult to change , but if there are any tricks I need to know, I would sure appreciate the information.

Thanks