Yes, 12v system with an alternator and reduction starter, and upgraded wiring. Most of the upgrades and work do appear well thought out and well done, but there were some boo boo's too. A few years ago when my nephew first brought it to me for some work, I could hear a knocking from the lower end. Upon teardown of the fairly fresh "rebuild", I found that the rebuilder had left out the locating pins for the main bearing shells. A crank grind and bearings AND locating pins cured that problem.
The sending unit in the head is for an aftermarket gauge, which formerly was in the hole in the dash to the left of the instrument cluster. It was in-op and I replaced it with a cheap mechanical unit which died after about two years. I left the sending unit in to plug the hole and used the hole in the top rear of the head for the mechanical gauge. Nephew wants it back to stock ( or stockish, and I agree) and we will put an oil pressure gauge in the dash hole.
1955CJ-5, I ordered that sender from Walck's. Looks like what I need. I drive by that museum all the time but have yet to visit it. One of those things you always intend to do but don't seem to get to. I'll make an effort.
Thanks for all the input, it was very helpful. When I get the sending unit and gauges back in I will post the results.