Thank you so much for all your reponses! They were all very helpful. I'm not gonna quote you all just to avoid spam and big messages.
So yes I totally bought the wrong one, and seems like it's gonna be hard to find the right one...
http://www.motomobil.com/throttle-co...1654540-1.html
This one might work out well, and I really think it's the same actually but it wasn't made for my Sierra generation. Maybe I'll send them a mail.
Anyway I'm gonna post another pic tomorrow to show you what kind of tensor the cable has (which is in my opinion the biggest difference between all the cables) and the way it's broken, so maybe I could figure something else out.

Again, thank you so much to you all for your time and I'll keep posting on here!