Jay-Bob
Were you doing any other jobs at the same time? You removed a few of things which I was able to leave in place, so I was wondering if you perhaps did glow plugs at the same time or anything. Specifically the intake manifold and the coolant were aspects I didn't do, and I don't have small hands nor great mechanical abilities.
Clearly there is more than one way to skin a cat. Some people have good success working from below, but I could not get any of my tools onto the sender to remove the old one. As previously linked to, I followed post 10 of this thread. It was perfect. I didn't do step 1 though.
603 Oil Pressure Sending unit