Ford 250c - Replacing the Sending Unit - Part 1

I have a monster of a Ford tractor. I bought this at a pre-auction sale as a Ford 4600, not knowing it was really a 250c. I'm still learning as I go, this is my first tractor, first diesel engine, lot's of firsts.
The first goal I had was to replace the wiring. All of the original wiring was corroded, eaten through and useless. Part of that was the fuel gauge. I replaced the gauge cluster, but the gauge still didn't work. So I installed a basic fuel gauge, still no luck. Narrowed it down to a faulty sending unit, so here's the process of replacing that.