W123 history
 

I've been learning about Mercedes diesels from a good friend of mine, and he told me that Mercedes-Benz usually makes minor tweaks each year.
I was wondering if there is a good website (or maybe just a PDF floating around) that documents the changes made to the W123?

Some data
 

http://www.geocities.com/SiliconValley/Pines/6633/w123history.html

http://www.mercedes-w123.net/w123_brochures.htm

http://en.wikipedia.org/wiki/Mercedes-Benz_W123

http://www.rallye-info.com/carspecs.asp?car=473

http://www.club123d.org/events/page20.html

http://wikicars.org/en/Mercedes-Benz_W123