I just read this thread through from the beginning. Good work! Great to see someone else still running a 12V!
A few things I'll note. The 4500 and 5600 shifters also have that nut under the cap, just sometimes they unthread when you spin the whole knob. When you spin them back on, the nut usually doesnt start, and just pushes against the plastic cap. If it isn't there, it's been removed by someone.
Check with Zemco's 4x4 in Clare for your wiring tidbits, sometimes they will clip the harnesses. They may also have the 2wd swaybar you need.
Once you are happy with the leaf set-up in the rear, you should replace the u-bolts. They do stretch and are supposed to be one use wonders.
Great info with the Dakota Digital, good option for the 12V guys looking to swap from a 241 to a 271 T-case.
How is your insurance set up? When I was hotshotting a few years back, they wouldn't insure us with a truck over five years old, IIRC. Maybe it was just super expensive.