Very purrty (I'm not much of a Benz man, but my father has always been and I can appreciate them, at least), but it can't be a '73 model. The S-class went to the W116 chassis for the 1973 model year. The only two years when the 280SEL 4.5 was made in the W108 chassis (which is pictured) were 1971 and 1972.

In many ways, the W108 chassis is more beautiful than the W116. The W116 is the more recognizable, but the W108 is more classic.

Fred or Jon, do you remember if the fuel injection on the SE/SEL models was electronic or mechanical? I seem to remember Mercedes had a really interesting mechanical injection system for a while. Probably a nightmare to service, but interesting nonetheless.