That's what I thought as well. I got mine off e-bay and figured it was an older model. It won't plug in because of two end pins on the M11. The M8 FM module has a space that the two pins fit freely in, so it will fit, I just don't know if the m11 will work with it.
Mike W
I know you can CAREFULLY drill 2 holes for the 2 extra pins on the older spektrum so it will fit in the m11. The only problem with it is you'll have to turn on your m11 first and then push in the module for it to work in the M11. I'm not sure what those 2 pins do, but it must have something to do with the module turning on. I would guess you could do the same thing with the FM module.