Hello everyone!

I got a hand-me-down Aurora R6 from my buddy. I've been looking on these forums for a little bit, but I can't find anything that specifically targets what I'm trying to do. Lots of close things, but not exactly. Sticking with the Alienware motherboards, which ones will fit perfectly or at least almost perfectly into my R6 case? Several of the case designs look completely identical. Like from the outside, I couldn't tell the R6 from the r7 or 8. Even looking at photos of the raw motherboards themselves outside of a case, they look identical, unless there's some really minute subtle differences that aren't evident from a picture. Does anyone know specifically if the R7, R8, or even R9 mobos will pop in my R6 case with little to no issue?