Fuel tank replacement

[Orange]

Hi

My Toyota Yaris 1999's fuel tank is leaking due to a rusty exterior. I have looked at the possibilities of sanding it down, but because it is very rusty, and I do not dare to use any power tools on it (because of possible explosion danger), I have decided that I want to purchase a new one.

However, the new tanks I have found surfing around the web are all said to be "empty" inside. My old tank does however contain some parts inside of it, for example some sort of a plastic container right underneath the fuel pump. These parts are sitting fastened inside the tank, and are too large to be removed through the top hole.

I am therefore wondering if I have to worry about new tanks having such parts inside? And, does anyone know exactly what these parts are for?

Thanks in advance. I can include pics if necessary.
Sincerely, norwegian who wants to keep driving his kickass 99 yaris