These rear springs fit the rear of the E36 and have red markings.  They came from my personal car, a 1998 328is (coupe).  The relaxed length is approximately 8 & 3/4".

Though they will likely fit all years I believe these are for the sport-suspension-equipped cars only. Please ask if you'd like more pictures.

Unfortunately my memory is a bit scant regarding interchange between the 328is and M3 rear springs, so please do all your research and/or match the markings in the photos before buying. These are sold as-is, no returns. I'll pack them carefully and ship them quickly.
Thanks for looking and please see my other listings for more E36 parts.