The sending unit should be accessible as it is a serviceable component. I had to remove mine and clean/tighten connections when we first purchased the coach and I don't remember it being too difficult.

Hi Mike I have 2003 Monaco Diplomat and I have a question about the fuel sending unit
I looked under the coach and it seems to be on the top of the tank which in my mind inaccessible unless the tank is removed is this correct. ?

Thanks
Neal Colingham