The wheels on the first jeep are simply CCKW rims trimmed with jeep bolt patterns welded into the centers. Very easy design, fits standard gauge (4ft 8.5in) quite well.
The one with the speeder wheels is a custom job. Spacers bolt to the jeep axle, then the standard speeder rims bolt to that.
There were speeder wheels that were made with the jeep bolt pattern and the correct offset already in place. The fella I bought my M38a1 from had a set in his shop. I should have bought them instead of the jeep!!!
the last set of photos are narrow gauge, probably 3ft. Not sure what the rims are off of. But they did the same thing, got the spacing right, and welded in the jeep centers.
If you flipped the front hubs on a deuce, and put just bare rims on, it would ride down the tracks quite nicely. I've got a set of hydraulic hyrail gear for the Air Force Railroad here, but they won't fit a pickup. but they will fit a deuce quite nicely.
I WILL drive my deuce on the rails one day, mark my words.