In service, I've only generally seen the C8 in a few variants;
C8 - Standard carbine, built in carry handle
C8A1 - flat top, C79 optical sight
C8A2 - Heavy barrel, Eotech sight, TRIAD RIS
That being said many troopies kit their weapons out with a variety of addons either out of pocket or with items bought by the unit. So a Diemaco DIS isn't really necessary for your impression. I've seen the Diemaco rear BUIS a bunch of times, but never the Diemaco stamped carry handle...
Perhaps someone on the pointy end can provide more guidance?
I believe he's talking about the carry handle seen here;