GU Sender Unit details and GRRRR browne davis tanks

my fuel sender stopped working in jan so i thought i'd check it out today. it finally wouldnt even let me pump fuel out of the sub tank which is really gay when you have run out of diesel but you kno you have 85 litres in the car....

anyway the cause is the main baffle in the browne davis tank has come totally loose and was sloshing around in the tank and has his the float arm , pushing it past the empty bump stop.

that was easy fixed, until i noticed it has smashed off a second pipe?

this pipe also has a small sendor unit on the bottom of it with a wire going up to the top. what does this do?

does anyone have access to wiring diags to tell me what this second sender is? could it be somethign to do with the fuel transfer from the sub tank which i know just pumps fuel up the filler neck and then it flows down into the main tank.

i'm going to ring browne davis on monday as i havent had these tanks 2 years yet. its pretty bad for the main internal baffle to break its welds

it will be a big job to have the baffle welded back in if i am paying, worst case i'll get some good tip snips and cut it up into little pieces inside the tank and pull them out the sender unit hole..

Grrrrr