Does anyone know if the Super 88 Convertible kick panels were carpeted, or just cardboard like the sedans, etc??

Also, has anyone tried to install 6 or 6 1/2" speakers in the kick panels of a non-AC 1956 Olds before??

 

I would just about guarantee they are cardboard. I don't think I have ever seen a car from that period with carpeted kick panels. I know the 54 convertible had cardboard. Can't help you with the speakers but you may consider putting them under the seat. Welcome to the site and we would love to see pictures of your car.