Top, first, thanks for your service.
This may be of some help in determining the differences between various models over the years.
http://tgmarsh.faculty.noctrl.edu/coleusstovemid50present.html
I'd suggest a two burner 413 series as these are fairly common and wider than the 425's allowing larger pots and pans. I have an "F" model from 1961 and the 1972 "G" I bought while in college. The "F" is my favorite due to its larger tank and adjustable legs. Go with one of the 426's if you'll need three burners. Let us know what you end up with a how it works out for you.