Jerry,
There were several variations in senders and other items through the years, in some cases dependent upon the cooling system configuration and year of manufacture. My motor is a 1987 4.108 and I have a Bowman Heat Exchanger mounted lengthwise on the left side of the engine. Some had their cooling systems mounted horizontally across the front of the engine.
The photo that shows #3 is the left rear of the engine. The dip stick to which you refer is the oil dip stick. Surely you've been checking this...where is yours located?
I believe your reference to "oil switch" (that triggers the low pressure alarm) is my item #1. Item #2 is the oil pressure sender that attaches to the oil pressure gauge.
I've attached some photos of my engine that's about ready to go back in as a reference for possible differences.