What I want to know is that is there any difference between those two controllers? If so, what are they? Are they completely interchangeable?
All help is appreciated!

Get the whole keyboard. A very early 1391401 is almost as desirable as a 1390131.Jersern wrote: ↑Yeah the 401 is from like 88 or 87. Alright, I'll try it out in a few days when I can get my hands on the spare controller.
If it is old enough, it has a very heavy metal back plate that is highly desirable. If you are doing bolt-mods, somebody will surely appreciate that plate.clickykeyboards wrote: ↑See my link for reference on different model M controllers.
http://www.clickeykeyboards.com/model-m ... 1987-1999/