I spent a year or three in graphic design and advertising. The image posted looks like it may have been taken by GM Photographic. In a studio. Then the background is “stripped in” as a step in creating the completed image. Many jobs that existed then are long obsolete as the computer revolution took hold in the 80s-90s. One was “strippers”, skilled jobs used daily to create and produce art for advertising and print. Another skilled craft was retouching, used to clean up or modify an image already taken. This job was taken over by Photoshop as noted. The airbrush was a key tool used by retouchers. Images used in creating dealer albums, model line brochures, etc were often modified by retouchers, sometimes due to final trim, color and so on may not have been finalized by the time these pieces had to be printed. You’ll see the disclaimers in these printed pieces noting that. Go to the GM Photostore, you’ll see many more images resembling the one posted.