Thanks for the compliments. Basically the coupe started in 1965 as a 2.0.
The E9 Designate began in 1968 and became a 2.8; 1971 - 3.0CS & CSI; 1972 - CSL (meaning light by some 300 lbs) and a 3.2 I believe. This model had, and still does have quite a racing history, and was in limited supply as were all E9's.
Refer to Wikipedia BMW E9 for more history.