I picked up a set of 4 used but like new Rainbow (German) speakers for the 124. My first question, all 4 seem to be identical --- is that right, or are there supposed to be 2 fronts and 2 rears? I had no trouble installing the Rainbows in the front and they sound good. But I can't get the rear speakers to fit in the plastic adapter ring (the one that the factory speakers are mounted in). There doesn't seem to be any way to get the Rainbows to be secured in that ring. Can anyone help??? Thanks much. PS I have the Rainbow instructions are they are not helpful as they are in German.