I am sure the picture is represented in multiple publications but it can be found in the "Mercedes-Benz , SL W113 Series, 1963 - 1971, by Brian Long". Page 115. The underlying caption advises that the picture was used in the 250 SL catalogue.
Norm
Added: I also found the picture in "Mercedes W113 The Complete Story by Myles Kornblatt". Page 82. The caption mentions: "The end of the line at the Sindelfingen plant shows the little differences for each market with a right hand drive car without side mirror, an Italian car with side marker lights, a French car with yellow headlights and an American car with the different headlight arrangement."