[W126 Coupe] speakers

[Shayegan, Richard]

I'm going to operate on the assumption that the SEC's have the same speaker mounts in the dashboard and rear deck as the SE's here, which may be wrong (I'm told by Crutchfield that the fronts are 3.5inch diameter and the rears are 4x6's on an SE, but I'm told by someone with an SE that they are all 4x6, so if someone can settle this that would be nice too), but either way, what are good speakers that fit that can be had for no more than $100/pair?
Thanks,
Richard