So I need 2, 55-9505 for the conversion. Correct?
LMC catalog says one 55-9505 and one 55-9506, which is what I ordered
Are these made in USA?
Nope, offshore for sure 
What guage wire is used?
appears to be 12 ga, maybe some 14
Mostly finished the install today, at least all the wiring, and was able to test the system. I offer some thoughts and notes below on how it went for me.
1. Lights. I went with the aftermarket lights from Headlights Depot off of Amazon. They are identical as those in the first post in this thread, and are made by TYC Lighting in Taiwan. They appear to be of good quality for what they cost - we shall see as time goes on.
2. Harnesses. As was covered above, many used the ones from SUV Lights. SUV Lights appears to be out of business, so that left me with choices of Stern or LMC. After reading of long delays in getting parts from Stern, I went with LMC because I wanted them on-hand for this week, which is "truck upgrade" week for me (on vacation). The harnesses themselves I would say are of reasonable quality given their cost and place of origin. Note that they do not contain a place for fuses - this is a serious design flaw!! With the kind of current all these headlights draw, you will have a for sure fire if anything shorts out in these circuits. I added my own fuse holders with 20A fuses in all four hot legs. Other than this, my lesser gripes are they could have been a few inches longer, and I had to add some loom for extra protection on one of them.
3. Wiring. The first point of confusion for me was what was the difference between those two P/N of the LMC harnesses??? First off, the package that the LMC harnesses come in offer very little to no useful information about how to wire and connect them. Next, I called LMC to try and find out and their answering person did not know the time of day, basically reciting what the catalog page says, and that noone else was available for support. After giving up on them for help, I spent many hours reading every forum and post on this subject I could find, and found a lot of interesting information which increased my overall knowledge of the Ram headlights saga, but nothing specific to understanding the LMC harnesses. I did read here and elsewhere of guys using two of the 55-9505's - I am still confused by that and what the lights actually do when wired that way

. Next, I analyzed them side by side. The only fundamental difference between the them is, two of the three wires in the light sockets have the wires swapped, i. e. , the 55-9505 has the ground on pin "A", and the 55-9506 has the ground on the center pin "B". Hmmm, ok, what does this mean??? After studying several schematics I found, I noticed the 9007 bulb has the ground on the center pin. Aaa ha I thought, so that must mean the 55-9505 harness fires the 9004 bulbs, and the 55-9506 harness fires the 9007 bulbs. This seems to make sense, so I decided to start the installation and wiring.
4. Initial check out. I didn't put the new headlight housings back on yet, but I did install all the bulbs in the correct sequence... 9007... . 9004... . 9004... 9007. The lights go on so I know electrically, all is well. However, the initial test results still leave some confusion, and the fact LMC does not specifically indicate how these harnesses are designed to work doesn't help either. On low beam, it seemed both 9007s filaments (outboard bulbs) and one of the 9004 filaments (inboard bulbs) were lit (seems ok?). When switched to high beam, the second 9004 filaments lit (seems ok?). When switch back to low beam... . no change! I had to shut the lights off and turn back on for the second 9004 filaments to reset. Don't know if the relays are sticking or what.
If anyone using these LMC harnesses can offer any suggestions or confirmation of whether this is how they are supposed to work, I would love to hear it.