I cant seem to find any info on this. I have seen a WIDE array of flashlights on rails from pictures. Any help would be appreciated

All of the above:

M951 seems most prolific.  

But I've also seen M96's, as well as Insight M3X's, M600A Scout Lights, M900 VFG Lights, Pentagon Lights, and mounting hardware for a variety of handheld flashlights.  

Not to mention the old Surefire Classic series lights.  You would hardly be wrong if you mounted one of those on a "clone."  Otherwise, if you're just wanting to know what's considered suitable for the military, those are most of the ones I've seen issued.  

HTH,
~Augee