That plug from my understanding is for the 4wd system. Basically where your dump valve is would be another type of dump valve that would have electrical prongs sticking out for the plug. I’ll have to find one and snap a pic of what I’m talking about.
Your “switch” is just a valve for the manual transmission set up. The autos have the valve I described above. Regardless of the trans set up you have, you are good to go.