Hi, I'm looking at a lot of youtube videos in regards to a radio for an A5 but I read that they are compatible with other models. ex - Q5, A4 is this true? i can get a radio from a Q5, A4 and they are compatible between each other?

 

if all else fails, look at serial numbers. I don't know nearly as much about the Q series, but I do know that cars of the same generation such as the a4 and a6 have the same stereo (keeping trims and options in mind) and that for the b6 and b7 A series cars share the same head unit between the symphony and bose systems within the same trim options. so parts are interchangable, but chances are if they look the same on the front, and plugs look the same on the back that they will fit. but like I said, look at serial numbers!