How to test fuel sender

66 ddart \6 225. Ok fuel gauge has been tested when I removed the dash. It appears to function. I have replaced the old Voltage Limiter with a new one. I have replaced the old PCB board with a new one.
Fuel gauge does nothing when car is turned on/started. doesnt flinch.

The fuel tank has a huge dent in it like someone hit a huge rock.

How can I trace that voltage is getting all the way to the tank?
If that is good, then how can I test the Fuel Sending unit which is inside the tank?

I am thinking the huge dent could have broken the sender unit? Or also there may not even be a sender inside. The previous owner said he replaced the tank, and the gauge did not work.

Any ideas? I see new tank CR11A for $170 from Amazon,. New sender unit FG69A for $53 from Rockauto.

If I disconnect the sender wire at the tank (I think I can get at it) how do I ground it out? without exploding