Just want to thank all for all the info on the CS-1's. I'm very fond of my 3" that I purchased new back in 1988. Serial # AVTxxxx product code 104228 stamped with the 2 and M. Still have the box (blue & white as mentioned previously) and papers that came with it.
Would love to eventually pair it up with a 4" but funds won't allow that currently.

I'll try and post a pic this evening