Hey all...thanks for the input...
I switched the wires on the dual sender and the gauge works...

Now, I KNOW that I have an oil pressure problem.

At idle, fully warmed up, the pressure is reading about 8-9 psi.
At 2000 rpm, the Bentley says 29psi...My gauge says about 18-20psi.
It's very clearly on the low side. Even when I rev it up to
almost 3000, it's not getting to 29psi.

So, do you think I'm in for a new oil pump? Lifters?
What else could be causing this? Should I get the 150% pump?
Do I have to drop the engine again, or can I just unbolt it
and lower the back end?
What about the screen inside the engine block for the oil?
Can this get clogged?

Thanks again...